If Tim can paint 2 square feet per minute, how fast can he paint a 10 foot by 8 foot wall?" *

The 95% confidence interval for the fraction of all shoppers during the year whose visit was because of a coupon they'd received in the mail is (0.2016, 0.2694).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

A store randomly samples 603 shoppers over the course of a year and finds that 142 of them made their visit because of a coupon they'd received in the mail.

This means that $n = 603, \pi = \frac{142}{603} = 0.2355$

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a p-value of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.2355 - 1.96\sqrt{\frac{0.2355*0.7645}{603}} = 0.2016$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.2355 + 1.96\sqrt{\frac{0.2355*0.7645}{603}} = 0.2694$

The 95% confidence interval for the fraction of all shoppers during the year whose visit was because of a coupon they'd received in the mail is (0.2016, 0.2694).

8 0

2 years ago

If f(x)=3x-2,find f(8)-f(-5)

Alexandra [31]

To find both f(8) and f(-5), we will need to plug in their values for x and solve for each. Then, we can subtract them to find the final answer.

Finding f(8):

f(8) = 3(8) - 2

f(8) = 24 - 2

f(8) = 22

Finding f(-5):

f(-5) = 3(-5) - 2

f(-5) = -15 - 2

f(-5) = -17

Subtracting f(8) and f(-5):

f(8) - f(-5)

22 - - 17

22 + 17

39

Hope this helps!! :)

6 0

3 years ago

a scuba diver, who was 25 2/3 feet beneath the surface of the water, descended 5 1/2 feet. from this depth, how many feet must t

Effectus [21]

Answer:

31 1/6 feet

Step-by-step explanation:

add 25 2/3 to 5 1/2 to see how far under the surface he is; use common denominator of 6

25 4/6 + 5 3/6 = 30 7/6

30 7/6 is the same as 30 + 1 1/6 so diver must ascend 31 1/6 feet

6 0

3 years ago