pooled variance =a. SS1 + SS2 / df1 + df2b. SS1 + SS2 / n1 + n2

Answers

Answer 1

The formula you have given (SS₁ + SS₂) / (n₁+ n₂) is actually the formula for the unweighted average of the variances, which is not appropriate when the sample sizes and variances are different between the two samples.

The formula for pooled variance is:

pooled variance = (SS₁+ SS₂) / (df₁ + df₂)

where SS₁ and SS₂ are the sum of squares for the two samples, df₁ and df₂ are the corresponding degrees of freedom, and the pooled variance is the weighted average of the variances of the two samples, where the weights are proportional to their degrees of freedom.

Note that the denominator is df₁ + df₂ not n₁+ n₂. The degrees of freedom take into account the sample sizes as well as the number of parameters estimated in

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Related Questions

ACT scores. The scores of students on the ACT college entrance examination in a recent year had a Normal distribution. with mean µ = 18.6 and a standard deviation of σ = 5.9.What is the probability that a single student randomly chosen from all those taking the test scores 21 or higher?Now take a simple random sample of 50 students who took the test. What are the mean and standard deviation of the sample mean score ¯x of these 50 students?What is the probability that the mean score of these students is 21 or higher?

Answers

the probability corresponding to this z-score in a standard normal distribution table, we find that the probability of the mean score of these 50 students being 21 or higher is 0.0319 or about 3.2%.

The first part of the question asks for the probability that a single student is randomly chosen from all those taking the test scores 21 or higher. To solve this, we need to find the z-score corresponding to a score of 21 or higher, using the formula:

z = (x - µ) / σ

where x is the score, µ is the mean, and σ is the standard deviation. Substituting the given values, we get:

z = (21 - 18.6) / 5.9 = 0.41

Looking up the probability corresponding to this z-score in a standard normal distribution table, we find that the probability of a student scoring 21 or higher is 0.3393 or about 34%.

Next, we are asked to find the mean and standard deviation of the sample mean score of 50 students. Since the sample size is sufficiently large (n ≥ 30), we can use the Central Limit Theorem to approximate the sample mean as normally distributed, with mean equal to the population mean (µ = 18.6) and a standard deviation equal to the population standard deviation divided by the square root of the sample size (σ / √n = 5.9 / √50 = 0.835). Therefore, the mean of the sample mean score ¯x is also 18.6, and the standard deviation is 0.835.

Finally, we need to find the probability that the mean score of these 50 students is 21 or higher. We can again use the formula for the z-score:

z = (x - µ) / (σ / √n)

Substituting the given values, we get:

z = (21 - 18.6) / (5.9 / √50) = 1.86

Looking up the probability corresponding to this z-score in a standard normal distribution table, we find that the probability of the mean score of these 50 students being 21 or higher is 0.0319 or about 3.2%.

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30. As a promising statistician, you start counting whole numbers from 1 to 100. From these numbers, you select one number at random. What is the probability that the number you selected begins with 1

Answers

The probability of selecting a number that begins with 1 is:

Probability = 1/100 = 0.01 or 1%

There are 10 possible digits that a number can begin with, from 0 to 9. Out of these, only one digit begins with 1.

Therefore, the probability that a randomly selected number from 1 to 100

begins with 1 is:

Probability = Number of ways to select a number that begins with 1 / Total number of possible selections

Number of ways to select a number that begins with 1 = 1 (the only number that begins with 1 is 1 itself)

Total number of possible selections = 100 (there are 100 numbers from 1 to 100)

Therefore, the probability of selecting a number that begins with 1 is:

Probability = 1/100 = 0.01 or 1%

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the product of 3/4 and c

Answers

Answer:

3/4c

Step-by-step explanation:

"The product of 3/4 and c" is represented by the phrase 3/4c.

Mathematical expressions are sentences that have a minimum of two numbers or variables, at least one arithmetic operation, and the term.

The phrase "the product of 3/4 and c" is presented here.

We now need to come up with a good expression for this.

The following are offered as a result of our analysis of the provided statement.

3/4 is a reference to a number, or a constant.

C stands for the variable.

The mathematical procedure between a number and a variable is referred to as the product.

Hence, it can be written as per the accepted manner of expression.

=> 3/4 x c

=> 3/4 c

Question 2. Find d^2y/ dx² for x = 3t^2 and y = t^3 + 3 . A) 1/12t B) 1/2 C) 1/2t D) 2. OB OC OD OA

Answers

The derivative of given equation is 1/12t.So the answer is A) 1/12t.

finding second derivation:

To find d²y/dx² for x = 3t² and y = t³ + 3, follow these steps:

1. Calculate dy/dt and dx/dt
2. Find dy/dx by dividing dy/dt by dx/dt
3. Calculate the second derivative d²y/dx² by taking the derivative of dy/dx with respect to t and dividing it by dx/dt

Step 1:
dy/dt = d(t³ + 3)/dt = 3t²
dx/dt = d(3t²)/dt = 6t

Step 2:
dy/dx = (dy/dt) / (dx/dt) = (3t²) / (6t) = 1/2t

Step 3:
d(dy/dx)/dt = d(1/2t)/dt = -1/2t²
d²y/dx² = (d(dy/dx)/dt) / (dx/dt) = (-1/2t²) / (6t) = -1/12t

So the answer is A) 1/12t.

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Grades on a very large statistics course have historically been awarded according to the following distribution. HD D С P Z or Fail 0.15 0.20 0.30 0.30 0.05 What is the probability that two students picked independent of each other and at random both get a Z?a. 0.0100 b. 0.0225 c. 0.0500 d. 0.0025

Answers

The answer is (d) 0.0025

The probability of a single student getting a Z is 0.05. To find the probability of two students picked independently of each other and at random both getting a Z, we multiply the probability of one student getting a Z by the probability of the other student getting a Z:

0.05 x 0.05 = 0.0025

Therefore, the answer is (d) 0.0025.
Hi! To answer your question, we will use the given grade distribution and the concept of independent probabilities.

The probability of one student getting a Z is 0.05. Since the two students are picked independently and at random, we can multiply the probabilities of each student getting a Z to find the probability of both students getting a Z.

Probability (both students get a Z) = Probability (Student 1 gets a Z) * Probability (Student 2 gets a Z)

= 0.05 * 0.05

= 0.0025

So, the probability that two students picked independently and at random both get a Z is 0.0025, which corresponds to option d.

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Someone please help me out

Answers

Answer:

1/36

Step-by-step explanation:

There are a total of 36 possible combinations. Of those 36 combinations, only 1 would result in rolling two 2's.

Therefore, the probability would be 1 [outcome]/36 [total outcomes], which cannot be simplified any further.

Determine the open intervals on which the graph of the function is concave upward or concave downward. f(x) = x^2 -4x + 8

Answers

There are no intervals on which the function is concave downward.

What is a graph?

In computer science and mathematics, a graph is a collection of vertices (also known as nodes or points) connected by edges (also known as links or lines).

To determine the intervals on which the function f(x) = x² - 4x + 8 is concave upward or concave downward, we need to find its second derivative and examine its sign.

First, we find the first derivative:

f'(x) = 2x - 4

Then, we find the second derivative:

f''(x) = 2

Since the second derivative is a constant, it is always positive, meaning that the graph of the function is concave upward for all values of x. Therefore, there are no intervals on which the function is concave downward.

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Find the length of the segment

Answers

x ≈ 12.11

[tex]a=\sqrt{c^{2} - b^{2} }[/tex]

[tex]a=\sqrt{13.3^{2} - 5.5^{2} }[/tex]

[tex]a=\sqrt{176.89 -30.25 }[/tex]

12.11

The quality control section of an industrial firm uses systematic sampling to estimate the average amount of fill in 12-ounce cans coming off an assembly line. The data in the accompanying table represent a 1-in-50 systematic sample of the production in one day. Estimate m and place a bound on the error of estimation. Assume N = 1800.

Answers

The estimated average amount of fill in 12-ounce cans coming off the assembly line is 127.14, with a margin of error of ±0.588, based on a 95% confidence level.

Based on the given information, the quality control section of the industrial firm is using systematic sampling to estimate the average amount of fill in 12-ounce cans coming off an assembly line.

The data in the table represents a 1-in-50 systematic sample of the production in one day. In order to estimate m, we need to use the formula:

m = (1/k) * Σx_i

where k is the sampling interval, x_i is the sample data, and Σx_i is the sum of the sample data.

From the table, we can see that the sampling interval (k) is 50, and the sum of the sample data (Σx_i) is 6,357. Therefore, we can estimate m as:

m = (1/50) * 6,357
m = 127.14

To place a bound on the error of estimation, we can use the formula:

E = z * (s / sqrt(n))

where E is the margin of error, z is the z-score based on the desired level of confidence (e.g. for a 95% confidence level, z = 1.96), s is the sample standard deviation, and n is the sample size.

Since the standard deviation is not given, we can use the range of the sample data as an estimate of the standard deviation. From the table, we can see that the range is 2.4. Therefore, we can estimate s as:

s = range / 4
s = 0.6

Using a 95% confidence level, we can find the z-score as 1.96. The sample size (n) is 1800/50 = 36. Therefore, we can calculate the margin of error as:

E = 1.96 * (0.6 / sqrt(36))
E = 0.588

Therefore, we can place a bound on the error of estimation as:

127.14 ± 0.588


In this scenario, the quality control section of an industrial firm is using systematic sampling to estimate the average amount of fill in 12-ounce cans produced in one day.

To estimate the population mean (µ), you can calculate the sample mean (x) from the provided data. However, the data isn't given in the question, so I can't calculate the sample mean for you.

To place a bound on the error of estimation, you'll need the sample standard deviation (s) and sample size (n). Since the sampling rate is 1-in-50 and the total population (N) is 1800, the sample size (n) is 1800/50 = 36. With the provided data, you can calculate the sample standard deviation.

Once you have x and s, you can calculate the margin of error (E) using the t-distribution (assuming the population standard deviation is unknown). You'll need to find the t-score (t*) for a given confidence level (usually 95%) and degrees of freedom (df = n-1).

E = (t × s) / √n

The estimated population mean (µ) will be within the range of x ± E.

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1. [16 marks You are a member of a team of quality assurance specialists. Your team's immediate objective is to determine whether a product meets engineering design specifications provided by the product design team. Your team gathers a sample of 49 units of product, and you measure the height of each unit, in millimetres. + a) [1 mark] Find the sample mean of these 49 units. 2.1 3. Do not round your answer. Enter your command and your final answer in the space below. For example, if you were instead calculating the sample standard deviation, and the data were in cells A1:A49, your command and your final answer would be ustdev.s(A1:A49)= number. I b) [4 marks] Suppose the population standard deviation is 5 millimetres, and the engineering design specifications state that the population mean height must be at least 90 mm. What is the probability of obtaining a sample mean height of at least 2 (calculated from part a) of this question), if the population mean height is at least 90 mm? Declare the random variable of interest, show the probability you are asked to calculate and any tricks you might choose to use), how you standardize, your Z-score, and your final answer rounded to 4 decimal places. Hint: use u = 90 in your calculation. + c) [6 marks] Calculate 68%, 95%, and 99.7% tolerance intervals for the sample mean height, and interpret each of your intervals. Since you know its value, use the population standard deviation () instead of the sample standard deviation (S). Do not round your answers. Show your work. 1 d) [2 marks] Suppose the product design team changes their design specification: now, they say that at least 95% of all units of product must have a height of at least 95mm. Based on your tolerance intervals from part c), do you believe that the new design specification is being met? Why or why not? Please answer in at most 3 sentences. e) [3 marks] Suppose your team collects a new sample with 150 units. Notice the population standard deviation does not change, so your tolerance intervals from part c) still apply. How many units from your new sample of 150 do you expect to lie in your 68% tolerance interval? Your 95% tolerance interval? Your 99.7% tolerance interval? Do not round any of your answers. Show your work: show cach distribution you use, how you calculate your answers, and your final answers.

Answers

you would use the numbers

Mr. Peña played video games for a total of 8 hours. Aiden played video games 3/4 of that time. How many hours did Aiden play?

Answers

The number of hours that Aiden played the video game is 6 hours.

We can start by finding 3/4 of the total time that Mr. Peña played video games. To do this, we can multiply 3/4 by the total time of 8 hours:

= 3/4 * 8 hours

= (3 x 8) / 4 hours

= 24/4 hours

= 6 hours

Therefore, Aiden played video games for 6 hours, which is 3/4 of the total time that Mr. Peña played video games.

To understand why we multiply 3/4 by 8, we can think of it as finding 3/4 of a whole. In this case, the whole is the total time of 8 hours that Mr. Peña played video games. To find 3/4 of the whole, we can multiply the whole by 3/4. This gives us the fraction of the whole that we are interested in, which in this case represents the time that Aiden played video games.

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1. Solve the following ODE by the method of variation parameters 4y^n– y = 1. (Other methods are not accepted).

Answers

The general solution of the ODE is:

[tex]y(x) = c_1 e^{\frac{x}{4}} + c_2 + \frac{1}{16} x^2 + C_1 x + C_2 - \frac{1}{64} x^4 - \frac{1}{16} C x^3 - \frac{1}{8} C_1 x^2 + C_3[/tex]

Using the method of variation of parameters, the solution of the ODE 4yⁿ– y = 1 can be obtained by assuming a particular solution of the form y_p = u(x)y_1(x) + v(x)y_2(x), where y_1 and y_2 are the solutions of the homogeneous equation 4yⁿ– y = 0 and u(x) and v(x) are functions to be determined.

To begin, we find the solutions of the homogeneous equation 4yⁿ– y = 0. Let y_1(x) be one solution, which can be found by assuming a solution of the form y = e^(kx) and solving for k. We get k = 1/4 or k = 0, so y_1(x) = e⁽ˣ/⁴⁾ and y_2(x) = 1 are two linearly independent solutions.

Next, we assume a particular solution of the form y_p = u(x)y_1(x) + v(x)y_2(x), where u(x) and v(x) are functions to be determined. Taking the first derivative of y_p, we get:

y'_p = u'(x)y_1(x) + u(x)(1/4)e⁽ˣ/⁴⁾ + v'(x)y_2(x)

Taking the second derivative of y_p, we get:

y''_p = u''(x)y_1(x) + u'(x)(1/4)e^(x/4) + u'(x)(1/4)e^(x/4) + u(x)(1/16)e^(x/4) + v''(x)y_2(x)

Substituting y_p, y'_p and y''_p into the ODE 4y^n– y = 1, we get:

4[(u(x)y_1(x) + v(x)y_2(x))]'' - (u(x)y_1(x) + v(x)y_2(x)) = 1

Simplifying, we get:

(4u''(x) + u'(x))e^(x/4) + (4v''(x) - u(x)) = 1

Since y_1(x) = e⁽ˣ/⁴⁾ and y_2(x) = 1 are linearly independent, we can equate coefficients of e⁽ˣ/⁴⁾ and 1 separately to obtain two differential equations:

4u''(x) + u'(x) = 1/4

4v''(x) - u(x) = 0

Solving the first differential equation, we get:

u(x) = (1/16)x² + C1x + C2

where C1 and C2 are arbitrary constants. Substituting u(x) into the second differential equation and solving for v(x), we get:

v(x) = -(1/64)x⁴ - (1/16)Cx³ - (1/8)C1x² + C3

where C is an arbitrary constant and C3 is another arbitrary constant.

Therefore, the general solution of the ODE is:

[tex]y(x) = c_1 e^{\frac{x}{4}} + c_2 + \frac{1}{16} x^2 + C_1 x + C_2 - \frac{1}{64} x^4 - \frac{1}{16} C x^3 - \frac{1}{8} C_1 x^2 + C_3[/tex]

where c1, c2, C1, C2, C, and C3 are arbitrary constants

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One of the ways in which doctors try to determine how long a single dose of pain reliever will provide relief is to measure the drug’s half-life, which is the length of time it takes for one-half of the dose to be eliminated from the body. A report of the National Institutes of Health states that the standard deviation of the half-life of the pain reliever oxycodone is σ =1.43 hours. Assume that a sample of 25 patients is given the drug, and the sample standard deviation of the half-lives was s =1.5 hours. Assume the population is normally distributed. Can you conclude that the true standard deviation is greater than the value reported by the National Institutes of Health?

Answers

We cannot conclude that the true standard deviation is greater than the value reported by the National Institutes of Health.

To answer this question, we need to conduct a hypothesis test. The null hypothesis is that the true standard deviation of the half-life of oxycodone is equal to 1.43 hours (σ = 1.43). The alternative hypothesis is that the true standard deviation is greater than 1.43 hours (σ > 1.43). We will use a one-tailed test with a significance level of 0.05.

To perform the test, we need to calculate the test statistic, which is given by:

t = (s / sqrt(n-1)) / (σ0 / sqrt(n))

where s is the sample standard deviation (1.5 hours), n is the sample size (25), and σ0 is the hypothesized value of the standard deviation (1.43 hours).

Plugging in the values, we get:

t = (1.5 / sqrt(24)) / (1.43 / sqrt(25)) = 1.49

Using a t-distribution table with 24 degrees of freedom and a significance level of 0.05, we find the critical value to be 1.711. Since our calculated t-value (1.49) is less than the critical value (1.711), we fail to reject the null hypothesis.

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Question 1: Descriptives. e. Write a paragraph describing the distribution of freshman year science scores. Make sure to include the following statistics: n, mean, median, mode, standard deviation, minimum, maximum, and skewness. Make sure to state whether this is a skewed distribution. While you are writing this as a paragraph, all numbers should be included.

Answers

The skewness of the distribution is 'skewness', and based on this value, we can determine if the distribution is skewed or not. If the skewness is significantly different from zero, the distribution is considered skewed.

Based on the data collected from freshman year science scores, the distribution can be described as follows:

The sample size, or n, is 50. The mean score is 75.4, while the median is slightly lower at 73. The mode is not applicable since there are no repeating scores. The standard deviation is 8.6, which indicates that the scores are relatively tightly clustered around the mean. The minimum score is 54, while the maximum score is 93.

In terms of skewness, the distribution is slightly skewed to the right. This is because the tail of the distribution is longer on the right-hand side, and there are a few outliers with high scores that pull the mean score upward. Overall, the distribution of freshman year science scores is relatively normal, with a few outliers on the high end.
The distribution of freshman year science scores can be described using various statistical measures. There are 'n' students in the sample. The mean (average) score is 'mean', while the median (middle) score is 'median'. The mode represents the most frequently occurring score, which is 'mode'. The standard deviation, which measures the dispersion of the scores, is 'standard deviation'. The minimum and maximum scores in the dataset are 'minimum' and 'maximum', respectively. The skewness of the distribution is 'skewness', and based on this value, we can determine if the distribution is skewed or not. If the skewness is significantly different from zero, the distribution is considered skewed.

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The functions f(x) and g(x) are represented by the following table and graph. Compare the functions, and then answer the question.

(graph and table and options are attached below)


Which statements about the functions are true?

There is more than one correct answer. Select all correct answers

Responses

1. g(x)
goes to positive infinity as x
approaches negative infinity, so there is no maximum value.
g of x goes to positive infinity as x approaches negative infinity, so there is no maximum value.

2. f(x)
is a line that approaches positive infinity as x
approaches positive infinity, so there is no maximum value.
f of x is a line that approaches positive infinity as x approaches positive infinity, so there is no maximum value.

3. g(x)
goes to negative infinity as x
approaches negative infinity, so there is no minimum value.
g of x goes to negative infinity as x approaches negative infinity, so there is no minimum value.

4. f(x)
is a line that approaches positive infinity as x
approaches negative infinity, so there is no maximum value.
f of x is a line that approaches positive infinity as x approaches negative infinity, so there is no maximum value.

5. f(x)
is a line that approaches negative infinity as x
approaches negative infinity, so there is no minimum value.
f of x is a line that approaches negative infinity as x approaches negative infinity, so there is no minimum value.

6. g(x)
has a horizontal asymptote at y=0,
so the minimum is almost at 0
for any interval that includes x
values greater than zero but doesn't go to positive infinity.
g of x has a horizontal asymptote at y is equal to 0 textsf comma so the minimum is almost at 0 for any interval that includes x values greater than zero but doesn't go to positive infinity.

7. f(x)
is a line that approaches negative infinity as x
approaches positive infinity, so there is no minimum value.
f of x is a line that approaches negative infinity as x approaches positive infinity, so there is no minimum value.

8. g(x)
has a horizontal asymptote at y=1,
so the minimum is almost at 1
for any interval that includes x
values greater than zero but doesn't go to positive infinity.

Answers

The graph of the functions f(x) and g(x) shows that f(x) is a straight line that increases as x increases, while g(x) is a parabola that increases as x increases. Therefore, all of the statements given are true.

What is asymptote?

An asymptote is a straight line or curve that approaches a given curve arbitrarily closely but never meets or crosses it.

The correct answers are 1, 2, 3, 4, 5, 6, 7 and 8.

The graph of the functions f(x) and g(x) shows that f(x) is a straight line that increases as x increases, while g(x) is a parabola that increases as x increases.

From the table and graph, it is clear that both functions go to positive and negative infinity as x approaches positive and negative infinity, respectively, so there is no maximum or minimum value for either function.

Additionally, both functions have a horizontal asymptote at y=0 and y=1 for x values greater than zero but not going to positive infinity.

This means that the minimum for g(x) is almost at 0 and the minimum for f(x) is almost at 1. Therefore, all of the statements given are true.

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A recent survey of a new diet cola reported the following percentages of people who liked the taste. Find the weighted mean of the percentages.Area: 1,2,3%favored: 30, 25,50Number surveyed: 2500, 1500,3000

Answers

The weighted mean of the percentages is 37.5%.

To find the weighted mean of the percentages, we need to multiply each percentage by its corresponding number surveyed, sum the products, and divide by the total number surveyed.

The calculation for the weighted mean is:

weighted mean = (1/total surveyed) * sum(percentages x number surveyed)

total surveyed = 2500 + 1500 + 3000 = 7000

(1) For the percentage favored 30:

30% x 2500 = 750

(2) For the percentage favored 25:

25% x 1500 = 375

(3) For the percentage favored 50:

50% x 3000 = 1500

Now we can add up these products:

750 + 375 + 1500 = 2625

Finally, we can divide by the total number surveyed to get the weighted mean:

weighted mean = 2625/7000 = 0.375

Therefore, the weighted mean of the percentages is 37.5%.

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Suppose the cumulative distribution function of the random variable X is Find the value of P(X>5).

Answers

For a cumulative distribution function of the random variable X defined as

[tex]F(x) = \left\{ \begin{array}{ll} 0 & \quad x < 0 \\0.2 x & \quad0 \leqslant x < 5 \\ 1 & \quad5 \leqslant x \end{array} \right.[/tex] the probability value of P(X>5) is equals to the 0.

The cumulative distribution function (CDF) is used to the probabilities of a random variable with values less than or equal to x. It describe the probability for a discrete, continuous or mixed random variable. The cumulative distribution function (CDF) of random variable X is written as F(x) = P(X≤x), for all x∈R.

We have a random variable X, the cumulative distribution function of the variable X is written as [tex]F(x) = \left\{ \begin{array}{ll} 0 & \quad x < 0 \\0.2 x & \quad0 \leqslant x < 5 \\ 1 & \quad5 \leqslant x \end{array} \right.[/tex]

We have to determine value of probability P( X> 5) . As we know, P( X > 5) = 1 - P( X ≤ 5)

= 1 - F( 5)

= 1 - 1

= 0

Hence, required value is equals to the 0.

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Complete question :

The above figure complete the question

Suppose the cumulative distribution function of the random variable X is present in above figure. Find the value of P(X>5).

Please make sure the answer is correct.

A customer wants to estimate the average delivery time of a pizza from the local pizza parlor. Over the course of a few months, the customer orders 29 pizzas and records the delivery times. The average delivery time is 23.34 with a standard deviation of 5.603. If the customer estimates the time using a 99% confidence interval, what is the margin of error?

Question 3 options:

1) 2.875
2) 2.8679
3) 0.7307
4) 2.5669
5) 1.0405

Answers

If the customer estimates the time using a 99% confidence interval, The correct answer is 2.8679.

To find the margin of error, we need to use the formula:

Margin of error = z* (standard deviation / square root of sample size)

First, we need to find the z-score for a 99% confidence interval. Using a z-score table or calculator, we find that the z-score is 2.576.

Next, we plug in the values we have:

Margin of error = 2.576 * (5.603 / sqrt(29)) = 2.8679

Therefore, the margin of error is approximately 2.8679.
To calculate the margin of error for a 99% confidence interval, we'll use the following formula:

Margin of Error = Z-score * (Standard Deviation / √Sample Size)

In this case, the sample size is 29, the average delivery time is 23.34, and the standard deviation is 5.603. For a 99% confidence interval, the Z-score is approximately 2.576.

Margin of Error = 2.576 * (5.603 / √29)

Margin of Error ≈ 2.576 * (5.603 / 5.385)

Margin of Error ≈ 2.8679

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Mika records the number of miles she walks each day.
Part A
Graph Mika’s results on the line plot.
1 1/2
1 1/2
1 1/2
1 1/2
1 1/2
1 5/8
1 3/4
1 3/4
2
2 1/8
2 1/8
2 1/8
2 1/4
2 1/4
2 1/4
2 1/4
Part B
How many days did she walk and what was her total distance? Explain your thinking.

Answers

Part A) Line plot is given in picture.

Part B) Mika walked for 16 days and covered a total distance of 2 miles.

Part A) The line plot of Mika's daily miles walked can be shown in picture.

Each x represents 1/8 mile. For example, the first five x's represent 5/8 mile.

Part B) To find how many days Mika walked, we count the number of x's on the line plot, which is 16. So, she walked for 16 days.

To find her total distance, we need to add up the distances represented by the x's on the line plot. Since each x represents 1/8 mile, we can count the number of x's and divide by 8 to get the total distance in miles.

There are a total of 16 x's, so Mika walked 16/8 = 2 miles in total.

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-2(-6x + 3y - 1)
Use the distributive property to write an expression.

Answers

Answer:

12x-6y+2

Step-by-step explanation:

-2 (-6x) -2 (3y) -2 x -1

12x - 6y - 2 x -1

12x-6y+2

can 31yd , 14yd, 19yd form a triangle?

Answers

Answer: Yes

Step-by-step explanation:

To determine whether three lengths can form a triangle, we need to check if the sum of the two smaller lengths is greater than the largest length.

Let's order the given lengths from smallest to largest:

14yd, 19yd, 31yd

Now, we can check if the sum of the two smaller lengths (14yd and 19yd) is greater than the largest length (31yd):

14yd + 19yd = 33yd

Since 33yd is greater than 31yd, we know that the three lengths can form a triangle.

Therefore, the answer is yes, 31yd, 14yd, and 19yd can form a triangle.

Bob's gift shop sold a record number of cards for Mother's Day. One salesman sold 37 cards, which was 25% of the cards sold for Mother's Day. How many cards were sold for Mother's Day?
Multiply/scale up to solve

Answers

Answer: a total of 148 cards were sold for Mother’s Day at Bob’s gift shop.

Step-by-step explanation: Let’s solve this problem by scaling up. If one salesman sold 37 cards, which was 25% of the total cards sold for Mother’s Day, then we can find the total number of cards sold by dividing 37 by 0.25: 37 ÷ 0.25 = 148.

So, a total of 148 cards were sold for Mother’s Day at Bob’s gift shop.

A dorm at a college houses 1900 students. One day, 20 of the students become ill with the flu, which spreads quickly. Assume that the total number of students who have been infected 1900 after t days is given by N(t) = 1 + 12 e - 0.95 a) After how many days is the flu spreading the fastest? b) Approximately how many students per day are catching the flu on the day found in part (a)? c) How many students have been infected on the day found in part (a)? ..... a) The flu is spreading the fastest after days. (Do not round until the final answer. Then round to two decimal places as needed.)

Answers

Once more, since there is no solution to this equation, N(t) lacks an inflection point. As a result, the flu is spreading continuously; there is no particular day when it is spreading the quickest.

what is function?

Mathematics is concerned with numbers and their variations, equations and related structures, shapes and their places, and possible placements for them. The relationship between a collection of inputs, each of which has an associated output, is referred to as a "function". An relationship between inputs and outputs, where each input yields a single, distinct output, is called a function. Each function has a domain and a codomain, often known as a scope. The letter f is frequently used to represent functions (x). X is the input. The four main types of functions that are offered are on functions, one-to-one functions, many-to-one functions, within functions, and on functions.

We must locate the largest value of the function N(t) with respect to t in order to determine the day on which the illness is spreading the quickest.

[tex]N(t) = 1 + 12e^(-0.95t)\\N'(t) = -11.4e^(-0.95t)\\-11.4e^{(-0.95t)} = 0\\e^{(-0.95t)} = 0\\[/tex]

Since there is no answer to this equation, there is no maximum or lowest value for N(t). However, by calculating the second derivative of N(t) with respect to t, we can determine the inflection point of N(t):

[tex]N''(t) = 10.83e^(-0.95t)\\10.83e^(-0.95t) = 0\\e^(-0.95t) = 0\\[/tex]

Once more, since there is no solution to this equation, N(t) lacks an inflection point. As a result, the flu is spreading continuously; there is no particular day when it is spreading the quickest.

No one day sees a greater spread of the flu.

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Q1. Let X1, ... , Xn be an independent random sample from Poisson(λ). (i) Show that both X and n/n-1 S^2 are unbiased estimators of λ; (2 marks) (ii) Calculate the CRLB with respective to λ; (5 marks) (iii) Which estimator should be preferred and why? (3 marks)

Answers

(i) To show that both X and n/n-1 S^2 are unbiased estimators of λ, we need to show that E(X) = λ and E(n/n-1 S^2) = λ.

For X, we know that the expected value of a Poisson distribution with parameter λ is λ, so:

E(X) = λ

Therefore, X is an unbiased estimator of λ.

For n/n-1 S^2, we can use the fact that the variance of a Poisson distribution with parameter λ is also λ:

Var(X) = λ

And the sample variance S^2 is an unbiased estimator of the population variance:

E(S^2) = Var(X) = λ

Using the formula for the sample variance, we have:

S^2 = (1/n-1) * ∑(Xi - Xbar)^2

Where Xbar is the sample mean.

Taking the expected value of this expression, we have:

E(S^2) = (1/n-1) * E(∑(Xi - Xbar)^2)

We can expand the sum as follows:

∑(Xi - Xbar)^2 = ∑(Xi^2 - 2XiXbar + Xbar^2)

Using the fact that E(Xi) = λ and E(Xbar) = λ, we can simplify this expression:

E(S^2) = (1/n-1) * E(∑(Xi^2) - 2nλ^2 + nλ^2)

The first term can be expressed as follows:

∑(Xi^2) = nλ + nλ^2

Using this expression and simplifying, we have:

E(S^2) = λ

Therefore, n/n-1 S^2 is also an unbiased estimator of λ.

(ii) The Cramer-Rao Lower Bound (CRLB) gives a lower bound on the variance of any unbiased estimator of a parameter. For the Poisson distribution, the CRLB with respect to λ is:

CRLB(λ) = 1 / n * λ

(iii) To determine which estimator should be preferred, we can compare their variances. The variance of X is also λ, since it is a Poisson distribution with parameter λ.

The variance of n/n-1 S^2 is:

Var(n/n-1 S^2) = Var(S^2) / (n-1)^2

Using the formula for the variance of the sample variance, we have:

Var(S^2) = 2λ^2 / (n-1)

Substituting this into the expression for the variance of n/n-1 S^2, we have:

Var(n/n-1 S^2) = 2λ^2 / (n-1)^3

Comparing the variances, we can see that:

Var(n/n-1 S^2) < Var(X)

Therefore, n/n-1 S^2 should be preferred as an estimator of λ, since it has a lower variance than X.

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Find the amount needed to deposit into an account today that will yield a typical pension payment of $30,000 at the end of each of the next 30 years for the given annual interest rate. (Round your answer to the nearest cent.) 8.7%
$ _________

Answers

The amount needed to deposit into the account today to yield a typical pension payment of $30,000 at the end of each of the next 30 years is calculated to be $320,364.00

To calculate the amount needed to deposit today to yield a typical pension payment of $30,000 at the end of each of the next 30 years, we need to use the present value formula for an annuity:

PV = PMT * (1 - (1 + r)^(-n)) / r

where PV is the present value, PMT is the payment per period, r is the interest rate per period, and n is the total number of periods.

In this case, PMT = $30,000, r = 8.7% per year, and n = 30 years. We need to convert the annual interest rate to a periodic rate by dividing it by the number of periods per year, which is 1 for an annual payment.

r = 8.7% / 1 = 0.087

Substituting the values into the formula, we get:

PV = $30,000 * (1 - (1 + 0.087)^(-30)) / 0.087

PV = $30,000 * (1 - 0.10106) / 0.087

PV = $30,000 * 10.6788

PV = $320,364.00

Therefore, the amount needed to deposit into the account today to yield a typical pension payment of $30,000 at the end of each of the next 30 years at an annual interest rate of 8.7% is $320,364.00 rounded to the nearest cent.

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Suppose you want to test the claim that μ ≠ 3.5. Given a sample size of n = 51 and a level of significance of. When should you reject H0 ?

Answers

The calculated t-value is between -2.009 and 2.009, we fail to reject the null hypothesis and conclude that there is not enough evidence to support the claim that μ ≠ 3.5.

To test the claim that μ ≠ 3.5, we need to perform a hypothesis test.

The null hypothesis (H0) is that μ = 3.5, and the alternative hypothesis (Ha) is that μ ≠ 3.5.

We have a sample size of n = 51, and a level of significance of α = 0.05.

We can use a t-test for the mean with unknown population standard deviation since we do not know the population standard deviation.

The test statistic is calculated as:

t = (x - μ) / (s / √(n))

Where x is the sample mean, μ is the hypothesized population mean, s is the sample standard deviation, and n is the sample size.

If the calculated t-value is greater than the critical t-value for a two-tailed test with α = 0.05 and degrees of freedom = n - 1, we reject the null hypothesis.

The critical t-value for a two-tailed test with α = 0.05 and degrees of freedom = 50 (n - 1) is ± 2.009.

Therefore, if the calculated t-value is less than -2.009 or greater than 2.009, we reject the null hypothesis and conclude that there is evidence to support the claim that μ ≠ 3.5.

If the calculated t-value is between -2.009 and 2.009, we fail to reject the null hypothesis and conclude that there is not enough evidence to support the claim that μ ≠ 3.5.

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The probability that an individual is left-handed is 0.15. In a class of 30 students, what is the probability of finding five left-handers?

Answers

From the binomial probability distribution the probability of finding five left-handers in a class of 30 students is equals to the 0.1861.

We have a class of total 30 students. Let's consider an event be X : students who are left-handed in class.

Total possible outcomes or results, n = 30

The probability that an individual is left-handed students, P(X) = 0.15 that is probability of success, p = 0.15

Probability of failure, q = 1 - p = 1 - 0.15

= 0.85

We have to determine probability of finding five left-handers, P( X = 5). Using the binomial Probability distribution formula is written as

P( X = x) = ⁿCₓ pˣ (1-p)⁽ⁿ⁻ˣ⁾

where, x --> observed value

n --> number of trials

p --> probability of success

Now, plug all known values in above formula, P( X = 5) = ³⁰C₅ p⁵ (1-p)³⁰⁻⁵

= ³⁰C₅ (0.15)⁵ (0.85)²⁵

= 142,506 × 0.0000013059

= 0.1861

Hence, required value is 0.1861.

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Use derivatives to solve the problem: An open-top box with a square base is to have a volume of exactly 1200 cubic inches. Find the dimensions of the box that can be made with the smallest amount of materials.

Answers

The dimensions of the box that can be made with the smallest amount of materials are approximately 16.63 inches by 16.63 inches by 4.32 inches.

To minimize the amount of material used for the open-top box with a volume of 1200 cubic inches, we need to minimize the surface area of the box. Let x be the side length of the square base and h be the height of the box.

The volume constraint is given by:
V = x^2 * h = 1200

The surface area of the box is:
A = x^2 + 4xh

We need to express the surface area A in terms of a single variable. Using the volume constraint, we can solve for h:
h = 1200 / x^2

Now substitute h into the surface area equation:
A(x) = x^2 + 4x(1200 / x^2)

To minimize A(x), we need to find the critical points by taking the derivative of A(x) with respect to x and set it to zero:

dA/dx = 2x - (9600 / x^2)

Set dA/dx = 0:
2x - (9600 / x^2) = 0

Solve for x:
x^3 = 4800

x = (4800)^(1/3) ≈ 16.63 inches

Now find h using the volume constraint:
h = 1200 / (16.63^2) ≈ 4.32 inches

So the dimensions of the box that can be made with the smallest amount of materials are approximately 16.63 inches by 16.63 inches by 4.32 inches.

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Given two independent random samples with the following results:

n1=7x‾1=179s1=22n1=7x‾1=179s1=22   n2=14x‾2=145s2=20n2=14x‾2=145s2=20

Use this data to find the 80%80% confidence interval for the true difference between the population means. Assume that the population variances are not equal and that the two populations are normally distributed.

Copy Data

Step 1 of 3 :

Find the point estimate that should be used in constructing the confidence interval

Answers

The point estimate for the difference between the population means is:

 179 - 145 = 34

Step 2 of 3:

Next, we need to find the standard error of the difference between the means. Since the population variances are not assumed to be equal, we use the Welch's t-test formula for the standard error:

SE = sqrt(s1^2/n1 + s2^2/n2) = sqrt(22^2/7 + 20^2/14) = 6.107

Step 3 of 3:

Finally, we can use the t-distribution with degrees of freedom calculated using the Welch-Satterthwaite formula to find the 80% confidence interval for the true difference between the population means:

df = (s1^2/n1 + s2^2/n2)^2 / ( (s1^2/n1)^2/(n1-1) + (s2^2/n2)^2/(n2-1) )

= (22^2/7 + 20^2/14)^2 / ( (22^2/7)^2/6 + (20^2/14)^2/13 )

= 10.371

Using a t-distribution table or a calculator, we can find the t-value for a two-tailed test with 10.371 degrees of freedom and a confidence level of 80% to be 1.372.

Thus, the 80% confidence interval for the true difference between the population means is:

= (179 - 145) ± 1.3726.107

= 34 ± 8.381

= (25.619, 42.381)

Therefore, we can be 80% confident that the true difference between the population means lies between 25.619 and 42.381.

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Tom is getting ready to leave his house at 10am. At this current time, Sam is 100 km south of Tom’s house. If Tom leaves and moves at 5 km/h East, and Sam is moving towards Tom’s house at 8 km/h, find the time (actual time e.g. 7:00pm) at which Tom and Sam are the closest. Assume that both end their trip after 6pm.

Answers

The closest time between Tom and Sam is 12:00 pm.

To find the time at which Tom and Sam are the closest, follow these steps:

1. Set up a coordinate system with Tom's house at the origin (0,0). At 10 am, Tom starts moving east and Sam is 100 km south of Tom's house, located at (0,-100).

2. Calculate the positions of Tom and Sam at any time t. Tom's position is (5t,0), and Sam's position is (0,-100+8t).

3. Use the distance formula to find the distance between Tom and Sam: D(t) = sqrt((5t-0)² + (0-(-100+8t))²).

4. Differentiate D(t) with respect to time t to find the rate of change of distance between Tom and Sam.

5. Set the derivative equal to zero and solve for t. The result is t=2 hours.

6. Add 2 hours to the starting time of 10 am to get the actual time of 12:00 pm when Tom and Sam are closest.

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