Answer:
The z score when x =72 is:
[tex] z = \frac{72-58}{11}= 1.273[/tex]
The mean is 58
This z-score tells you that x= 72 is 1.273 standard deviations to the right of the mearn.
Step-by-step explanation:
Assuming the following info for the question: Suppose John's words per minute on a typing test are normally distributed. Let X -the number of words per minute on a typing test. Then X N(58, 11) If necessary, round to three decimal places.
Provide your answer below rds per minute in a typing test on Sunday. The z score when x =72 is
For this case we know that the variable of interest is modelled with the normal distribution:
[tex]X \sim N (\mu= 58, \sigma=11)[/tex]
And the z score is given by:
[tex] z = \frac{X -\mu}{\sigma}[/tex]
And replacing we got:
[tex] z = \frac{72-58}{11}= 1.273[/tex]
The mean is 58
This z-score tells you that x= 72 is 1.273 standard deviations to the right of the mearn.
sum what is the sum of 199+ -24=
?
Answer:
175
Step-by-step explanation:
+ × - = -
thus 199+(-24)
199-24
175
Answer: 199 + -24 = 175
Step-by-step explanation: 199 is a positive number and -24 is a negative number. If the positive number is bigger than the negative number you subtract. So forget that the - sign is there and subtract it.
Given A triangle with sides x=6.35 cm and Y=12.25 cm with an angle of 90 degrees between them, find the length of the hypotenuse and the size of the other two angles.
Answer:
Hypotenuse = 13.798 cm, Angle1 = 27.4° and Angle2 = 62.59°
Step-by-step explanation:
The first step to help us understand the question would be to draw it out.
A right angled triangle, with the two sides that make the right angle being x and y (it does not matter which way you put x and y).
I have attached the quick sketch I will refer to.
To find the length of the hypotenuse (lets call it H) we can use Pythagoras theorem as shown below
[tex]{x^{2}+y^{2}} = H^{2}[/tex]
Substitute in our values for x and y, and solve for H
[tex]{6.35^{2}+12.25^{2}} = H^{2}[/tex]
[tex]190.385 = H^{2}[/tex]
[tex]\sqrt{190.385} = H[/tex]
H = 13.79 cm
To find the other two angles of the triangle we will use trigonometry
I will first look for angle ∅. Since we have all three sides of the triangle we can use any of the three trig functions, I chose to use Tan
Tan ∅ [tex]= \frac{opposite}{adjacent}[/tex]
Substitute in our values for x and y, and solve for ∅
Tan ∅ = [tex]\frac{6.35}{12.25}[/tex]
∅ = [tex]tan^{-1} \frac{6.35}{12.25}[/tex]
∅ = 27.4°
Now do the same for angle β. I chose to use Tan again
Tan β [tex]= \frac{opposite}{adjacent}[/tex]
Substitute in our values for x and y, and solve for β
Tan β = [tex]\frac{12.25}{6.35}[/tex]
β = [tex]tan^{-1} \frac{12.25}{6.35}[/tex]
β = 62.59°
please help you will get 20 points and explain your answer please
Answer:
Top prism = 262 in.² Bottom prism = 478 in.²
Step-by-step explanation:
top prism:
front + back: 5 x 3 = 15
sides: 19 x 4 x 2 = 152
bottom: 19 x 5 = 95
15 + 152 + 95 = 262
bottom prism:
front + back: 5 x 6 x 2 = 60
sides: 19 x 6 x 2 = 228
top + bottom: 19 x 5 x 2 = 190
60 + 228 + 190 = 478
Answer:
Top prism = 262 in.² Bottom prism = 478 in.²
Step-by-step explanation:
top prism:
front + back: 5 x 3 = 15
sides: 19 x 4 x 2 = 152
bottom: 19 x 5 = 95
15 + 152 + 95 = 262
bottom prism:
front + back: 5 x 6 x 2 = 60
sides: 19 x 6 x 2 = 228
top + bottom: 19 x 5 x 2 = 190
60 + 228 + 190 = 478
A phone charger requires 0.5 A at 5V. It is connected to a transformer with 100 % of efficiency whose primary contains 2200 turns and is connected to 220-V household outlet.
(a) How many turns should there be in the secondary?
(b) What is the current in the primary?
(c) What would be the output current and output voltage values if number of secondary turns (N2) doubled of its initial value?
Answer:
a. 50 turns
b. 0.0114 A
c. 0.25 A, 10 V
Step-by-step explanation:
Given:-
- The required current ( Is ) = 0.5 A
- The required voltage ( Vs ) = 5 V
- Transformer is 100% efficient ( ideal )
- The number of turns in the primary coil, ( Np ) = 2200
- The Voltage generated by power station, ( Vp ) = 220 V
Find:-
a. The number of turns in the secondary coil of the transformer
b. The current supplied by the power station
c. The effect on output current and voltage when the number of turns of secondary coil are doubled.
Solution:-
- For ideal transformers that consists of a ferromagnetic core with two ends wounded by a conductive wire i.e primary and secondary.
- The power generated at the stations is sent to home via power lines and step-down before the enter our homes.
- A household receives a voltage of 220 V at one of it outlets. We are to charge a phone that requires 0.5 A and 5V for the process.
- The outlet and any electronic device is in junction with a smaller transformer.
- All transformers have two transformation ratios for current ( I ) and voltage ( V ) that is related to the ratio of number of turns in the primary and secondary.
Voltage Transformation = [tex]\frac{N_p}{N_s} = \frac{V_p}{V_s}[/tex]
Where,
Ns : The number of turns in secondary winding
- Plug in the values and evaluate ( Ns ):
[tex]N_s = N_p*\frac{V_s}{V_p} \\\\N_s = 2200*\frac{5}{220} \\\\N_s = 50[/tex]
Answer a: The number of turns in the secondary coil should be Ns = 50 turns.
- Similarly, the current transformation is related to the inverse relation to the number of turns in the respective coil.
Current Transformation = [tex]\frac{N_p}{N_s} = \frac{I_s}{I_p}[/tex]
Where,
Ip : The current in primary coil
- Plug in the values and evaluate ( Ip ):
[tex]I_p = \frac{N_s}{N_p}*I_s\\\\I_p = \frac{50}{2200}*0.5\\\\I_p = 0.0114[/tex]
Answer b: The current in the primary coil should be Ip = 0.0114 Amp.
- The number of turns in the secondary coil are doubled . From the transformation ratios we know that that voltage is proportional to the number of turns in the respective coils. So if the turns in the secondary are doubled then the output voltage is also doubled ( assuming all other design parameters remains the same ). Hence, the output voltage is = 2*5V = 10 V
- Similary, current transformation ratio suggests that the current is inversely proportional to the number of turns in the respective coils. So if the turns in the secondary are doubled then the output current is half of the required ( assuming all other design parameters remains the same ). Hence, the output current is = 0.5*0.5 A = 0.25 A
A consultant built an Einstein Analytics dashboard for a shipping company. The dashboard displays data from several data sources. The consultant enabled data sync (replication) to increase the speed of data refreshing from these sources. What is the maximum number of dataflow definitions available in this situation?
A. 30
B. 45
C. 25
D. 35
Answer: A (30)
Step-by-step explanation:
By defaults, data will be enabled in tens. And it increases by replicating the initial value.
There is no way the maximum number of dataflow definitions available in this situation will be 45, 25 or 35
The only possible replicant that can be available is 30
Please answer this correctly
Answer:
20-39 => 2
40-59 => 1
60-79 => 1
80-99 => 6
100-119 => 5
Answer: 2, 1, 1, 6, 5
Step-by-step explanation:
20-39
2 | 3
3 | 9
40-59
5 | 0
60-79
7 | 5
80-99
8 | 1 2 4
9 | 3 9 9
100-119
10 | 1 1 5 6
11 | 1
What is the m
10
50
90
180
Use the Intermediate Value Theorem to show that there is a root of the given equation in the specified interval.
x4 + x ? 7 = 0, (1, 2)
f(x) = x4 + x ? 7
is (FILL IN)
a) defined
b) continuous
c) negative
d) positive on the closed interval [1, 2],
f(1) = ?? FILL IN , and f(2) = ?? FILL IN
Since ?5 < FILL IN a)? b)? c)? d)0 < 11, there is a number c in (1, 2) such that
f(c) = FILL IN a)? b)? c)0 d)11 e)-5
by the Intermediate Value Theorem. Thus, there is a FILL IN a) limit b)root c) discontinuity of the equation
x4 + x ? 7 = 0
in the interval (1, 2).
Answer:
The correct option is d
[tex]f(1) = -5[/tex]
[tex]f(2) = 11[/tex]
The correct option is d
The correct option is c
the correct option is b
Step-by-step explanation:
The given equation is
[tex]f(x) = x^4 + x -7 =0[/tex]
The give interval is [tex](1,2)[/tex]
Now differentiating the equation
[tex]f'(x) = 4x^3 +7 > 0[/tex]
Therefore the equation is positive at the given interval
Now at x= 1
[tex]f(1) = (1)^4 + 1 -7 =-5[/tex]
Now at x= 2
[tex]f(2) = (2)^4 + 2 -7 =11[/tex]
Now at the interval (1,2)
[tex]f(1) < 0 < f(2)[/tex]
i.e
[tex]-5 < 0 < 11[/tex]
this tell us that there is a value z within 1,2 and
f(z) = 0
Which implies that there is a root within (1,2) according to the intermediate value theorem
PLEASE HELP the inverse of the function graphed below is a function
True or false
Functions
Function NotationVertical Line Test
ApplicationStep 1: DefineLet's see what we are given.
We are given a graph of an inverse of a function.
Step 2: IdentifyWe need to figure out whether the graphed inverse function is a function or not.
By the definition of a function, we know that every x input must correlate with one y output. In layman's terms, each respective x input has its own specific y output.
This definition builds the foundation of the Vertical Line Test. We can use this simple "tool" to verify whether or not a given graph is a function or not.
By placing a vertical line "on" the graph, we can move it to determine whether an x input has only one y output.If a graph passes the Vertical Line Test, it is said to be a function.If a graph fails the Vertical Line Test, it is said to not be a function, but rather a relation, etc.Step 3: TestWhen we apply the Vertical Line Test to the graphed inverse function, we can see that every x input has only one specific y output.
∴ we can conclude that the graphed inverse function is indeed a function.
AnswerThe answer to the question would be A. True.
___
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___
Topic: Algebra I
Unit: Functions
Find the length of side x in simplest radical form with a rational denominator
Answer:
[tex] x = 7 \sqrt{3} [/tex]
Step-by-step explanation:
[tex] \tan \: 30 \degree = \frac{7}{x} \\ \\ \therefore \: \frac{1}{ \sqrt{3} } = \frac{7}{x} \\ \\ x = 7 \sqrt{3} \\ [/tex]
Solve for x: 3x - 5 = 2x + 6.
Your answer
Answer:
3x-5=2x+6
x-5=6
x=11
Jake made a rectangular garden area as shown in the figure. He wants to add 3 inches of topsoil to the entire area.
36 in
15 in
How much topsoil does Jake need to get at the nursery?
540 in.
1,080 in.
1,386 in.
1,620 in.
Answer:
1,620in
Step-by-step explanation:
LxWxH
36 x 15 x 3 = 1,620 in
Answer:
1620
Step-by-step explanation:
A broker has calculated the expected values of two different financial instruments X and Y. Suppose that E(x)= $100, E(y)=$90 SD(x)= 90$ and SD(y)=$8. Find each of the following.
a. E(X+ 10) and SD(X+ 10)
b. E(5Y) and SD(5Y)
c) E(X+ Y) and SD(X+ Y)
d) What assumption must you make in part c?
Expectation is linear, meaning
E(a X + b Y) = E(a X) + E(b Y)
= a E(X) + b E(Y)
If X = 1 and Y = 0, we see that the expectation of a constant, E(a), is equal to the constant, a.
Use this property to compute the expectations:
E(X + 10) = E(X) + E(10) = $110
E(5Y) = 5 E(Y) = $450
E(X + Y) = E(X) + E(Y) = $190
Variance has a similar property:
V(a X + b Y) = V(a X) + V(b Y) + Cov(X, Y)
= a^2 V(X) + b^2 V(Y) + Cov(X, Y)
where "Cov" denotes covariance, defined by
E[(X - E(X))(Y - E(Y))] = E(X Y) - E(X) E(Y)
Without knowing the expectation of X Y, we can't determine the covariance and thus variance of the expression a X + b Y.
However, if X and Y are independent, then E(X Y) = E(X) E(Y), which makes the covariance vanish, so that
V(a X + b Y) = a^2 V(X) + b^2 V(Y)
and this is the assumption we have to make to find the standard deviations (which is the square root of the variance).
Also, variance is defined as
V(X) = E[(X - E(X))^2] = E(X^2) - E(X)^2
and it follows from this that, if X is a constant, say a, then
V(a) = E(a^2) - E(a)^2 = a^2 - a^2 = 0
Use this property, and the assumption of independence, to compute the variances, and hence the standard deviations:
V(X + 10) = V(X) ==> SD(X + 10) = SD(X) = $90
V(5Y) = 5^2 V(Y) = 25 V(Y) ==> SD(5Y) = 5 SD(Y) = $40
V(X + Y) = V(X) + V(Y) ==> SD(X + Y) = √[SD(X)^2 + SD(Y)^2] = √8164 ≈ $90.35
what is the diagonal of asquare with length 3cm
Answer:
3√2
Step-by-step explanation:
If you draw the diagonal, you have a 45°45°90° triangle.
The two legs are 3, so the hypotenuse is 3√2
Bonnie volunteers to bring bags of candy to her child's class for the Halloween party. She buys a bag containing 240, a bag containing 624, and a bag containing 336 pieces. Age needs to use all the candy to create identical treat bags. How many treat bags can bonnie make so that each one has the same number and variety of candy? How many of each type of candy will be in each bag?
Answer:
Number of bags that Bonnie can make so that each one has the same number of candies = 48
Number of candies from bag I in each of the treat bag = 5
Number of candies from bag II in each of the treat bag = 13
Number of candies from bag III in each of the treat bag = 7
Step-by-step explanation:
Given: One bag (I) has 240 candies, one bag (II) has 624 candies and one bag (III) has 336 candies
To find: Number of bags that Bonnie can make so that each one has the same number of candies and number of each type of candies in each bag
Solution:
[tex]240=2^4\times 3\times 5\\624=2^4\times3\times13\\336=2^4\times3\times7[/tex]
Highest common factor (H.C.F) = [tex]2^4\times3=48[/tex]
So,
Number of bags that bonnie can make so that each one has the same number of candies = 48
Now,
[tex]\frac{240}{48}=5\\ \frac{240}{48}=13\\\frac{240}{48}=7[/tex]
Number of candies from bag I in each of the treat bag = 5
Number of candies from bag II in each of the treat bag = 13
Number of candies from bag III in each of the treat bag = 7
Which rule represents the translation from he pre-image, ABCD, to the image, A’B’C’D’?
Answer:
Option (4)
Step-by-step explanation:
From the figure attached,
Quadrilateral ABCD has been translated to form an image A'B'C'D' by shifting 'a' units right and 'b' units up.
Let the rule for translation is,
(x, y) → (x + a, y + b)
Coordinates of point A is (-4, 4) and the coordinates of the image A' are (-2, 5).
So, (-4, 4) → [(-4 + 2), (4 + 1)]
Therefore, the translation can be represented by [tex]T_{2, 1}(x, y)[/tex] (shifted 2 units right and 1 unit up).
Option (4) will be the answer.
Answer:
T2,1(x,y)
Step-by-step explanation:
At the beginning of year 1, Paolo invests $500 at an annual compound
interest rate of 4%. He makes no deposits to or withdrawals from the
account.
Which explicit formula can be used to find the account's balance at the
beginning of year 5? What is the balance?
Answer:
see below
Step-by-step explanation:
The way the problem is worded, we expect "n" to represent the year number we're at the beginning of. That is the initial balance is that when n=1, and the balance at the beginning of year 5 (after interest accrues for 4 years) is the value of obtained when n=5.
After compounding interest for 4 years, the balance will be ...
500·1.04^4 = 584.93
The matching answer choice is shown below.
Answer:
b
Step-by-step explanation:
g Using a calculator, find the actual error in measuring volume if the radius was really 6.5 cm instead of 6 cm, and find the actual error if the radius was actually 5.5 cm instead of 6 cm. Compare these errors to the answer you got using differentials
Answer:
The answer is "[tex]58.625 cm^3[/tex]"
Step-by-step explanation:
Consider the cube volume of x =6 cm.
Substitute x = 6 cm in the volume
[tex]V= x^3\\\\ V = (6)^3\\\\ V = 216[/tex]
Therefore, whenever the cube volume
[tex]x=6 \ cm \ is \ V= 216 \ cm^3[/tex]
Then consider the cube's volume
x = 6.5 cm.
Substitute x = 6.5 cm in the volume
[tex]V_1 = x^3\\V_1 = (6.5)^3\\V_1 = 274.625 \\[/tex] by using the calculator.
Therefore, when another cube volume
[tex]x = 6.5 cm \\\\ V_1 = 274.625 cm^3.[/tex]
The real volume error x = 6.5 cm instead of x = 6 cm is calculated as,
[tex]dV= V_1-V\\[/tex]
[tex]=274.625-216\\=58.625\\[/tex]
Hence, the actual error in the volume when x = 6.5 cm instead of x = 6 cm is [tex]58.625 \ cm^3.[/tex]
Aisha needs to be at least 48 inches tall to ride the colossal coaster at the amusement park. If she grows 5 inches during the next year, Aisha will still not be tall enough to ride. In the context of this situation, what does the inequality x less-than 43 represent?
Answer:
Aisha is shorter than 43 inches.
Step-by-step explanation:
[tex]x+5=48[/tex]
[tex]x=48-5[/tex]
[tex]x=43[/tex]
[tex]x >43[/tex]
Answer:
The answer is B!
Step-by-step explanation:
Test taking! <3
determine whether the forces in the pair are pulling at right angles to each other for the values. a-3.4 and b=2.6, which are legs of a right triangle, find c, the hypotenuse, to the nearest tenth
Answer:
4.3 units
Step-by-step explanation:
In this question we use the Pythagorean Theorem which is shown below:
Data are given in the question
Right angle
a = 3.4
b = 2.6
These two are legs of the right triangle
Based on the above information
As we know that
Pythagorean Theorem is
[tex]a^2 + b^2 = c^2[/tex]
So,
[tex]= (3.4)^2 + (2.6)^2[/tex]
= 11.56 + 6.76
= 18.32
That means
[tex]c^2 = 18.56[/tex]
So, the c = 4.3 units
While filing your income tax, you report annual contributions of $100 to a public radio station, $300 to PBS (television station), $150 to a woman’s shelter, and $450 to other charitable organizations.
Find your monthly expense.
Hey there! I'm happy to help!
Let's add up all of these contributions.
100+300+150+450=1000
However, this is annual. We want monthly. So, we simply divide by 12.
1000/12≈83.33
Therefore, the monthly expense is $83.33
I hope that this helps! Have a wonderful day!
Find the value of x in the figure below. Round to the nearest tenth.
Answer:
16
Step-by-step explanation:
We can find x using tan 40° which can be represented as x/20. tan 40° is also equal to about 0.8 so that means x / 20 = 0.8 and x = 16.
what are 80 percent of 500
Answer: 400
Step-by-step explanation:
500 x 0.80 = 400
Answer:
400
Step-by-step explanation:
Of means multiply
80% * 500
Change to fraction form
80/100 * 500
Rewriting to reduce
80 * 500/100
80 * 5
400
write eight hundred and seven thousand, two hundred and five in figures
Answer:
807,205
Step-by-step explanation:
Take the eight hundred and seven thousand and express that has 807,000. Then, add the two hundred and five at the end to get 807,205
The given statement is written in figures 807,205.
The given statement is eight hundred and seven thousand, two hundred and five in figures.
We need to write the given statement as the number.
What are numbers?A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words.
Now, eight hundred and seven thousand, two hundred and five=807,205.
Therefore, the given statement is written in figures 807,205.
To learn more about the numbers visit:
https://brainly.com/question/17429689.
#SPJ2
As a birthday gift, you are mailing a new personal digital assistant (PDA) to your cousin in Toledo. The PDA cost $414. There is a 3 percent chance it will be lost or damaged in the mail. Is it worth $4 to insure the mailing?Explain, using the concept of expected value.
Answer:
It is worth $4 to insure the mailing.
Step-by-step explanation:
The random variable X can be defined as the money value.
The PDA costs, $414.
It is provided that there is a 3% chance it will be lost or damaged in the mail.
So, there is 97% chance it will not be lost or damaged in the mail.
The insurance costs $4.
If the PDA is lost or damaged in the mail when there is no insurance the money value would be of -$414.
And if the PDA is lost or damaged in the mail when there is an insurance the money value would be of $414 - $4 = $410.
Compute the expected value of money as follows:
[tex]\text{E (X)}=(0.97\times 410)+(0.03\times -414)[/tex]
[tex]=397.7-12.42\\=385.28[/tex]
The expected value of money in case the PDA is lost or damaged in the mail or not is $385.28.
Thus, it is worth $4 to insure the mailing.
What’s the correct answer for this question?
Answer:
1)
Volume of pyramid = 1/3(Ab)(h)
Where Ab is the area of base, h is height
Volume of cone = 1/3(Ab)(h)
a) Their formula for finding volume is same. Also, their painting heads are same.
b) Pyramids have a tetragonal base while cones have a polygonal base
2) Pyramids
Volume of cone = (1/3) πr²h
Since Area of a circle = πr²
So
Volume of pyramid = (1/3)(A)(h)
So we can use the formula of a circle in cone's formula
Answer:
i dont know but i want points
Step-by-step explanation:
hehehe
f(x)=x^2-2x+3; f(x)=-2x+28
Answer:
(-5, 38) and
(5,18)
Step-by-step explanation:
[tex]x^2-2x+3=-2x+28\\<=> x^2-2x+3+2x=28\\<=> x^2 = 28-3=25\\<=> x^2-25=0\\<=> x^2-5^2 =0\\<=> (x-5)(x+5)=0\\<=> x = 5 \ or \ x=-5[/tex]
so the solutions are
(-5, 38) and
(5,18)
The following data summarizes results from 945 pedestrian deaths that were caused by accidents. If one of the pedestrian deaths is randomly selected, find the probability that the pedestrian was intoxicated or the driver was intoxicated.
Pedestrian
intoxicated not intoxicated
Driver intoxicated 64 68
not intoxicated 292 521
Answer:
37.67% probability that the pedestrian was intoxicated or the driver was intoxicated.
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
In this question:
945 accidents.
In 64 of them, the pedestian was intoxicated.
In 292 of them, the driver was intoxicated.
Probability that the pedestrian was intoxicated or the driver was intoxicated.
(64+292)/945 = 0.3767
37.67% probability that the pedestrian was intoxicated or the driver was intoxicated.
In ΔEFG, ∠E \cong≅∠G, GE = 7 and FG = 15. Find the length of EF.
Answer: EF = 15
Step-by-step explanation:
The given description is that of an isosceles triangle. The base angles are congruent, therefore the sides opposite of those angles are also congruent.
The base angles are ∠E and ∠G and the vertex angle is ∠F.
The sides opposite to the base angles are EF and FG.
Thus, EF ≡ FG.
Since FG = 15 and FG = EF, then 15 = EF.
Based on the definition of an isosceles triangle, the length of EF in the triangle is: 15 units.
What is an Isosceles Triangle?An isosceles triangle has two sides that are congruent. The angles opposite these congruent sides are also congruent.
ΔEFG is an isosceles triangle. The congruent sides are, FG and EF.
Therefore, EF = FG = 15 units.
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A charity receives 2025 contributions. Contributions are assumed to be mutually independent and identically distributed with mean 3125 and standard deviation 250. Calculate the approximate 90th percentile for the distribution of the total contributions
Answer:
The 90th percentile for the distribution of the total contributions is $6,342,525.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
For sums of size n, the mean is [tex]\mu*n[/tex] and the standard deviation is [tex]s = \sqrt{n}*\sigma[/tex]
In this question:
[tex]n = 2025, \mu = 3125*2025 = 6328125, \sigma = \sqrt{2025}*250 = 11250[/tex]
The 90th percentile for the distribution of the total contributions
This is X when Z has a pvalue of 0.9. So it is X when Z = 1.28. Then
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
By the Central Limit Theorem
[tex]Z = \frac{X - \mu}{s}[/tex]
[tex]1.28 = \frac{X - 6328125}{11250}[/tex]
[tex]X - 6328125 = 1.28*11250[/tex]
[tex]X = 6342525[/tex]
The 90th percentile for the distribution of the total contributions is $6,342,525.
