While doing an article on the high cost of college education, a reporter took a random sample of the cost of new textbooks for a semester. Her sample consisted of 20 students with a mean of $212.45 and a standard deviation of $38.92. A. Find the 99% confidence interval estimate of the true mean textbook cost for the semester based on her sample. Assume the cost of new textbooks is normally distributed.B. Based on part a, is an average cost of $200 for a semester a likely value for the population mean? Why or why not?

Answers

Answer 1

Answer:

The answer is below

Step-by-step explanation:

Given that:

mean (μ) = $212.45, standard deviation (σ) = $38.92 and sample size (n) = 20 students.

a) Confidence (C) = 99% = 0.99

α = 1 - C = 1 - 0.99 = 0.01

α/2 = 0.01/2 = 0.005

The z score of α/2 is the same as the z score of 0.495 (0.5 - 0.005) which is equal to 2.576. This means that Z(α/2) = 2.576

The margin of error (E) is given as:

[tex]E=Z_{\frac{\alpha}{2} }*\frac{\sigma}{\sqrt{n} } \\\\Substituting:\\\\E=2.576*\frac{38.92}{\sqrt{20} } \\\\E=8.7[/tex]

The confidence interval = (μ ± E) = (212.45 ± 8.7) = (203.75, 221.15)

Hence the 99% confidence interval is between 203.75 and 221.15.

b) The population mean is the same as the sample mean. Hence the population mean = $212.45


Related Questions

About 3/5th of the registered voters participated in 2016 election. California has 25 million registered voters. Find the number of registered voters who participated in 2016 election.

Answers

Answer:

Step-by-step explanation: 3x5=7056 = x25 2016

Help don’t understand

Answers

(-2 1/2, -7) Quadrant 3
(0,6)Y axis
X axis (-5,0)
Oop

Can you help me with this math problem? Im having a hard time with it, if you can explain it too that would help a lot. attachment below

Answers

Answer:

[tex]3^{-3}\cdot \:\:8^{-3}=\frac{1}{24^3}[/tex]

Thus, the equivalent expression is:  [tex]\frac{1}{24^3}[/tex]

Step-by-step explanation:

Given the expression

[tex]3^{-3}\cdot 8^{-3}[/tex]

[tex]\mathrm{Apply\:exponent\:rule}:\quad \:a^{-b}=\frac{1}{a^b}[/tex]

[tex]=8^{-3}\cdot \frac{1}{3^3}[/tex]

[tex]\mathrm{Apply\:exponent\:rule}:\quad \:a^{-b}=\frac{1}{a^b}[/tex]

[tex]=\frac{1}{3^3}\cdot \frac{1}{8^3}[/tex]

[tex]\mathrm{Multiply\:fractions}:\quad \frac{a}{b}\cdot \frac{c}{d}=\frac{a\:\cdot \:c}{b\:\cdot \:d}[/tex]

[tex]=\frac{1\cdot \:1}{3^3\cdot \:8^3}[/tex]

[tex]=\frac{1}{24^3}[/tex]

Thus,

[tex]3^{-3}\cdot \:\:8^{-3}=\frac{1}{24^3}[/tex]

Thus, the equivalent expression is:  [tex]\frac{1}{24^3}[/tex]

Write an recursive rule for the sequence 7,14,21,28

Answers

+ 7 every time......

A manufacturer of handcrafted wine racks has determined that the cost to produce x units per month is given by C=0.3X^2+8,000. How fast is the cost per month changing when production is changing at the rate of 14 units per month and the production level is 70 UNITS?


Costs are ___ at the rate of $___ per month at this production level.

Answers

Answer:

Costs are changing at the rate of $588 per month at this production level.

Step-by-step explanation:

From the question, we have:

C = 0.3X^2 + 8,000 ........................ (1)

Differentiating equation (1) with respect to time, t, we have:

dC/dt = (0.3 * 2) X (dX/dt)....................... (2)

Where;

X = 70

dX/dt = 14

Substituting this into equation (2), we have:

dC/dt = (0.3 * 2) * 70 * 14

dC/dt = 588

This implies that costs are changing at the rate of $588 per month at this production level.

Can someone help pls !

Answers

Answer:

(B). [tex]A_{y}[/tex] = [tex]\left[\begin{array}{cc}12&7\\17&-51\end{array}\right][/tex]

Step-by-step explanation:

12x - 13y = 7

17x - 22y = - 51

A = [tex]\left[\begin{array}{cc}12&-13\\17&-22\end{array}\right][/tex]

[tex]A_{x}[/tex] = [tex]\left[\begin{array}{cc}7&-13\\-51&-22\end{array}\right][/tex]

[tex]A_{y}[/tex] = [tex]\left[\begin{array}{cc}12&7\\17&-51\end{array}\right][/tex]

Find f(-2)for f(x)-3 . 2^x

Answers

B. 3/4 is the correct answer
Answer:

Yes B is correct

Explanation:

After you simplify the expression, the exact form is 3/4

Express the area of the entire rectangle.
Your answer should be a polynomial in standard form.

Answers

Answer:

x^2 + 11x + 24

Step-by-step explanation:

x^2 + 3x + 8x + 24 =

= x^2 + 11x + 24

sally has 2/8 cookies in a jar she ate 1/4 how many dose she have left :explain

Answers

Answer:

1.5 cookies if 2/8 is like 2 cookies out of 8, 1/16 if its like 2/8 of a cookie

Step-by-step explanation: \

1.5: 2 x 3/4 (already ate 1/4) = 1.5

1/16= 1/4 (2/8 reduced)  x 1/4

slope m=-2, point: (4,3)​

Answers

Answer:

Step-by-step explanation:

(y - 3) = -2(x - 4)

y = -2x + 8 + 3

y = -2x + 11

pls give brainliest

Answer:

The the linear equation in point-slope form is

[tex]y-3 = -2 (x-4)[/tex]

Step-by-step explanation:

Given

slope = m = -2point (4, 3)

We know that the point-slope form of the line equation is

[tex]y-y_1=m\left(x-x_1\right)[/tex]

Here:

m is the slope(x₁, y₁) is the point

substituting the values m = -2 and the point (4, 3) in the point-slope form

[tex]y-y_1=m\left(x-x_1\right)[/tex]

[tex]y-3 = -2 (x-4)[/tex]

Thus, the the linear equation in point-slope form is

[tex]y-3 = -2 (x-4)[/tex]

Note: This equation could be further simplified to write it in the slope-intercept form

[tex]y=mx+b[/tex]

where m is the slope and b is the y-intercept

so writing the equation in the slope-intercept form

[tex]y-3 = -2 (x-4)[/tex]

[tex]y-3 = -2x+8[/tex]

[tex]y=-2x+8+3[/tex]

[tex]y=-2x+11[/tex]

Thus, the equation is the slope-intercept form is

[tex]y=-2x+11[/tex]

Given f(x) = 2x2 – 3x + 7, find f(2.5)

Answers

Answer:

f(2.5)=3.5

Step-by-step explanation:

f(x)=2×2-3x+7

So,

f(2.5)=2×2-3×2.5+7

=4-7.5+7

=11-7.5

=3.5

Hope it will help you

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