A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores. Marketing managers are prone to look at the estimate and ignore sampling error. A random sample of 36 stores this year shows mean sales of 53 units of a small appliance with a standard deviation of 12 units. During the same point in time last year, a random sample of 49 stores had mean sales of 41 units with standard deviation 6 units.

It is of interest to construct a 95 percent confidence interval for the difference in population means ?1??2, where ?1 is the mean of this year's sales and ?2 is the mean of last year's sales.

Enter values below rounded to three decimal places.

(a) The estimate is: _________ .

(b) The standard error is: ____________________ .

Answers

Answer 1

Answer:

The 95% confidence interval for the difference of means is (7.67, 16.33).

The estimate is Md = 12.

The standard error is sM_d = 2.176.

Step-by-step explanation:

We have to calculate a 95% confidence interval for the difference between means.

The sample 1 (this year's sales), of size n1=36 has a mean of 53 and a standard deviation of 12.

The sample 2 (last year's sales), of size n2=49 has a mean of 41 and a standard deviation of 6.

The difference between sample means is Md=12.

[tex]M_d=M_1-M_2=53-41=12[/tex]

The estimated standard error of the difference between means is computed using the formula:

[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{12^2}{36}+\dfrac{6^2}{49}}\\\\\\s_{M_d}=\sqrt{4+0.735}=\sqrt{4.735}=2.176[/tex]

The degrees of freedom are:

[tex]df=n_1+n_2-1=36+49-2=83[/tex]

The critical t-value for a 95% confidence interval and 83 degrees of fredom is t=1.989.

The margin of error (MOE) can be calculated as:

[tex]MOE=t \cdot s_{M_d}=1.989 \cdot 2.176=4.328[/tex]

Then, the lower and upper bounds of the confidence interval are:

[tex]LL=M_d-t \cdot s_{M_d} = 12-4.328=7.67\\\\UL=M_d+t \cdot s_{M_d} = 12+4.328=16.33[/tex]

The 95% confidence interval for the difference of means is (7.67, 16.33).


Related Questions

Three dogs eat 30 pounds of food in 10 days. If each dog eats the same amount, how much food does 1 dog eat in 1 day? 1 pound 3 pounds 9 pounds 10 pounds

Answers

Answer:

Unable to read entire question, but see explanation for answer

Step-by-step explanation:

First, you need to find the unit rate per dog. If it takes 3 dogs 10 days to finish 30 pounds of food, then it takes 1 dog 1 day to finish 1 pound of food. I cannot read the entirety of the question because of the cropping, but you can find how much food a single dog eats in that amount of days by just multiplying by the number of days (say, 1 pound in 1 day, or 3 pounds in 3 days). Hope this helps!

Answer:

1

Step-by-step explanation:

took test

Simplify the following expression and then write down the coefficient of x²: x² + x² + x² + x²

Answers

Answer:

The expression is 4x² and coefficient is 4.

Step-by-step explanation:

All have the same variables, x², so you add up together :

[tex] 1{x}^{2} + 1{x}^{2} + 1{x}^{2} + 1{x}^{2} [/tex]

[tex] = 4 {x}^{2} [/tex]

What is the point-slope form of a line with slope 3 that contains the point
(2, 1)?

Answers

Answer:

y-1 = 3(x-2)

Step-by-step explanation:

The point slope form of a line is

y-y1 = m(x-x1)

where m is the slope and (x1,y1) is a point on the line

y-1 = 3(x-2)

4 ounces for every 16 ounces. Rate or ratio and in simplest form

Answers

4 for 16 would be written as 4/16.

Dividing both numbers by 4 it is simplified to 1/4

4 ounces for every 16 ounces can be written as:

[tex]\displaystyle \frac{4}{16} =\frac{1}{4}[/tex]

As a ratio, it can be expressed as:

[tex]1:4[/tex]

Help asap giving branlist!!!

Answers

Answer:

B

Step-by-step explanation:

Let's arrange it into slope-intercept form.

2x - y = 4

y = 2x - 4

We are looking for a line with slope of 2 and y-intercept -4. This line is Line B.

If 5=3+2,then 3+2=5. What is the truth value

Answers

Answer:

true

Step-by-step explanation:

How can sums and differences of cubes be identified for factoring?

Answers

Answer:

Step-by-step explanation:

The sum of two perfect cubes breaks down into two factors, the first is the sum of their cube roots, and the second is made up of the square of the first root minus the product of both roots plus the square of the second root.

The difference of two perfect cubes is decomposed into two factors, the first is the difference of their cube roots, and the second is made up of the square of the first root plus the product of both roots plus the square of the second root.


What’s the correct answer for this question?

Answers

Answer:

B

Step-by-step explanation:

In the attached file

Elena has a bottle that has a capacity of 34 quarts. What is the maximum amount of liquid that can be stored in this bottle?

Answers

I would say 8.5 gallons

Help??!!??!?!!??anyone

Answers

Answer:

A. 32.25

Step-by-step explanation:

Because of the first row, we know that to find the cost, we are multipling the gallons by 2.15.

so [tex]15*2.15=32.25[/tex]

So the answer is A.

Hope this helps!

Plx give brainliest

liam is a tyre fitter it takes him 56 minutes to fit 4 tyres to a van

Answers

Answer:

Step-by-step explanation:

I am not really sure because u did not finish the question but is u are asking how much time it takes to fit one tyre:

answer is time/tyres

56min./4

14 min. Per type

If the measure of the angle in the southwest corner of the intersection of Broadway and 21st Street is approximately 105ºwhat is the measure of the angle in the southwest corner of the intersection of Broadway and 22nd Street?

A: 85 degrees
B: 95 degrees
C: 120 degrees
D: 105 degrees

Answers

Answer:

95°

Step-by-step explanation:

The angle on the 20TH street and 22ND street must add up to 180° so the answer is 95°

Answer:

This isnt right. Good try though

Step-by-step explanation:

Anyone know the answer?

I promise brainliest and a exter 25 poinst to the first to answer What is the solution to the inequality 2x ≥ -4? Click the number line until the correct answer is shown...

Answers

:

Answer:

the answer is the arrow going to the right because its not a negative number and a closed circle

Step-by-step explanation:

so that means that 2x is at LEASt more than -4 opposed to this sign> wich just means greater than

because when you work with variables you usually cannot find the exact amount especially when you are rounding so you know that its biigger than no less than or at least -4

the answer is the arrow going to the right because its not a negative number and a closed circle

please please mark as brainliest

Use the area to find the radius. If you could include steps that’ll be very helpful :)

Answers

Answer:

Area = PI * radius^2

radius^2 = Area / PI

radius^2 = 169*PI/PI

radius^2 = 169

radius = 13

Step-by-step explanation:

Identify the exponential function for this graph. (Be sure to look at the scales
on the x- and y-axes.)

Answers

On the x axes thi nk I really don’t know

The required  exponential function will be F(x)= [tex]4(0.5)^{x}[/tex]

Hence, Option A is the correct.

What is function?

A relation between a collection of inputs and outputs is known as a function. A function is, to put it simply, a relationship between inputs in which each input is connected to precisely one output.

From the assumption graph as shown in attached figure, we can determine that when x = 0  then y = 4.

Also, we can closely observe that the graph represents decay  

exponential function.

The reason is that when the value of x   increases, the graph of the particular function decreases.

But, the rate of decay must be less than 1 for decay exponential function because if it is greater than 1, then it would represent  the exponential growth function.  

Hence, the option B and D should be completely ruled out as these values represent the exponential growth.  

And from graph, it is clear that when  x = 0 then y = 4

The exponential function will be F(x)= [tex]4(0.5)^{x}[/tex]

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Please answer this correctly

Answers

Answer:

0-19: Make it 4 units tall

20-39: Make it 2 units tall

40-59: Make it 5 units tall

60-79: Make it 3 units tall

80-99: Make it 1 unit tall

Step-by-step explanation:

0-19: 4, 6, 19, 19 (4 numbers)

20-39: 29, 38 (2 numbers)

40-59: 40, 41, 41, 57, 58 (5 numbers)

60-79: 62, 66, 73 (3 numbers)

80-99: 87 (1 number)

A survey asks teachers and students whether they would like the new school
mascot to be a shark or a moose. This table shows the results. Which
statement is true?

Answers

Is there any other information?

The average score of all golfers for a particular course has a mean of 70 and a standard deviation of 3.5. Suppose 49 golfers played the course today. Find the probability that the average score of the 49 golfers exceeded 71.

Answers

i don’t know the answer to that sorry

Solve (x + 1 < 4) ∩ (x - 8 > -7).

Answers

Answer:

[tex]1<x<3[/tex]

Step-by-step explanation:

Let simplify each of these inequalities individually and then look at where they intersect afterwards

[tex]x+1<4\\\\x<3[/tex]

And

[tex]x-8>-7\\\\x>1[/tex]

This means that for these two inequalities to intersect, x must be greater than 1, but less than 3.

This can be represented by the following inequality [tex]1<x<3[/tex]

this is the last one for the morning and may be some later

Answers

Answer:

A is correct Please brainliest me

Thus, also saying that it is equivalent.

Step-by-step explanation:

The expression stated- (3m+1-m)

It also states to give a equal amount

What is equalevent expression?- Equivalent expression are those expression  that looks different but are same.

For example, 2+2 is 4 and 1 plus 3 is 4

it is different expression but the same answer.

The Expression- 3m+1-m

Simplify. How?- By adding LIKE terms.

Here- 3m+ 1 - m = (3-1) m + 1

see the same.

To conclude, 3-1) m + 1  = 2m + 1

If you’d wanna write in another way, it would be 2m + 1 can be written as m + m + 2 - 1

so a is correct

A circle with circumference 6 has an arc with a 20 degrees central angle. What is the length of the arc?

Answers

Answer:

[tex]\frac{1}{3}[/tex]

Step-by-step explanation:

So first calculate what fraction of the circumference the arc is.

[tex]\frac{20}{360}=\frac{1}{18}[/tex]

Now the circumference is 6, so one eighteenth of that is [tex]\frac{1}{3}[/tex]

Find the measure of x:

Answers

Answer:

x=7

Step-by-step explanation:

Do the equation 8x+5 + 3x+8 = 90 and do the math to come out with 7

Hope this helps :)

Answer:

7*

Step-by-step explanation:

8x + 3x + 8 * + 5*=11x+13*

90*-13*=77*

77*= 11x

x= 77*/11=7*

* = degree

4. The Navarro family uses an average of 225 gallons of water per day, 5 gallons of water per day, 5 gallons of water which goes through the family’s water filter. The Navarros’ water filter can process 450 gallons before it needs to be replaced. After how many days of average water use will the family need to replace their filter?

Answers

Answer:

  90

Step-by-step explanation:

The family filters 5 gallons per day, so can expect to use the filter for ...

  (450 gal)/(5 gal/day) = 90 day

After 90 days of average water use, the family will need to replace the filter.

Angle θ is in standard position. If (8, -15) is on the terminal ray of angle θ, find the values of the trigonometric functions.

sin(θ) =

cos(θ) =

tan(θ) =

csc(θ) =

sec(θ) =
✔ 17/8

cot(θ) =
✔ -8/15
i have only gotten the last two right and i need help with the others.

Answers

Answer:

cos =1/ sec

=8/17

tan =1/cot

= -15/8

sin = 15/17 or -15/17

cosec = 1/ sin

= 17/15 or -17/15

Answer:

Did the same assignment. lol can see how that went but here's the answers. hope it helps.

(a^2-b^2) (c^2-d^2) +4abcd​

Answers

[tex]a^{2} {c}^{2} - {a}^{2} {d}^{2} - {b}^{2} {c}^{2} + {b}^{2} {d}^{2} + 4abc[/tex]

Find the characteristic polynomial and the eigenvalues of the matrix. [Start 2 By 2 Matrix 1st Row 1st Column 11 2nd Column 2 2nd Row 1st Column 2 2nd Column 11 EndMatrix ]The characteristic polynomial is nothing.

Answers

Answer:

Step-by-step explanation:

The answer is 3x 987 colunm 2

Simplify the given expression. Assume x doesn’t = 0. (20x^-3/10x^-1)^-2
X^4/2
X^4/4
X^2/4

Answers

Answer:

X^4

------

 4

Step-by-step explanation:

The simplified expression is 1/4x²  

What is a polynomial expression?

Polynomial is made up of two terms, namely Poly (meaning “many”) and Nominal (meaning “terms.”). A polynomial is an expression composed of variables, constants, and exponents, combined using mathematical operations such as addition, subtraction, multiplication, and division (No division operation by a variable). Based on the number of terms present in the expression, it is classified as monomial, binomial, and trinomial. For example P(x) = x²-5x+11

Given here, the expression is (20x⁻³ / 10x⁻¹)⁻² =2⁻²× x⁻²

                                                                             = 1/4x²

Hence, the simplified expression is  1/4x²

Learn more about polynomial expression here:

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3 of 6
As an estimation we are told £3 is €4.
Convert £85.40 to euros.
Give your answer rounded to 2 DP

Answers

Answer:

€113.67

Step-by-step explanation:

£3 = €4

£85.40 is €x

Cross multiply.

[tex]4 \times 85.4=3x[/tex]

[tex]3x=341.6[/tex]

[tex]\frac{3x}{3}=\frac{341.6}{3}[/tex]

[tex]x=113.86666...[/tex]

The company produces two types of goods in quantities of x and y, with market prices of €40 and 80€, respectively. If the production cost is given by function C(x,y) =2x^2+5y^2+120 and is not exceeding €250. What is the max profit obtained?

Answers

Answer:

€ 270

Step-by-step explanation:

Since the production cost C(x,y) = 2x² + 5y² + 120 is less than or equal to 250, we have  2x² + 5y² + 120 ≤ 250

The selling price S(x,y) = 40x + 80y

The profit P(x,y) = S(x,y) - C(x,y) = 40x + 80y - 2x² - 5y² - 120

Using the principle of lagrange multipliers, we want to maximize the profit P(x,y) under the condition that C(x.y) ≤ 250.

So, dP/dx = 40 - 4x , dC/dx = 4x, dP/dy = 80 - 10y , dC/dy = 10y

dP/dx + λdC/dx = 0

40 - 4x + 4λx = 0  (1)

4λx = 4x - 40

λ = (x - 10)/x

dP/dy + λdC/dy = 0

80 - 10y + 10λy = 0 (2)

substituting λ into (2), we have

80 - 10y + 10(x - 10)y/x = 0

multiplying through by x, we have

80x - 10xy + 10xy - 100y = 0

80x - 100y = 0

80x = 100y

x = 100y/80

x = 5y/4

substituting x into C(x,y) ≤ 250, we have

2(5y/4)² + 5y² + 120 ≤ 250

25y²/8 + 5y² + 120 ≤ 250

25y² + 40y² + 960 ≤ 2000

65y² ≤ 2000 - 960

65y² ≤ 1040

y² ≤ 1040/65

y² ≤ 16

y ≤ ±√16

y ≤ ± 4 since its quantity, we take the positive value.

So x = 5y/4 = 5(± 4)/4 = ± 5

So, x ≤ ± 5

For the maximum value for the profit, P(x,y), we take the maximum values of x and y which are x = 5 and y = 4. Substituting these values into P(x,y), we have

P(5,4) = 40(5) + 80(4) - 2(5)² - 5(4)² - 120

= 200 + 320 - 50 - 80 - 120

= 520 - 250

= 270

So, the maximum profit obtained is € 270

What is the equation of the line that passes through (4, 2) ) and is parallel to 3x - 2y = - 6 ?

Answers

Answer:

[tex]y=\frac{3}{2} x-4[/tex]

Step-by-step explanation:

The graph I provided shows it passes thru (4,2) and that it is parallel

Answer:

y = 3/2x -4

Step-by-step explanation:

3x - 2y = - 6

First find the slope by putting it in slope intercept form

Subtract 3x from each side

-2y = -3x-6

Divide by -2

y = -3x/-2  -6/-2

y = 3/2x +3

The slope is 3/2

Parallel lines have the same slope

We have the slope 3/2 and a point (4,2)

y = mx+b where m is the slope and b is the y intercept

y =3/2x+b

Substitute the point into the equation

2 = 3/2(4) +b

2 = 6 +b

Subtract 6

2-6 = 6-6+b

-4 =b

y = 3/2x -4

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