A commuter finds that she waits an average of

11.7

seconds at each of

six

stoplights, with a standard deviation of

9.4

seconds. Find the mean and the standard deviation of the total amount of time she waits at all

six

lights. What, if anything, did you assume?

The mean time she waits at all

six

lights is

enter your response here

seconds.

(Type an integer or a decimal.)

The standard deviation of the time she waits at all

six

lights is

enter your response here

seconds.

(Round to two decimal places as needed.)

What, if anything, did you assume? Multipule choice

A.

It is necessary to assume the wait times at the lights are independent to calculate both the mean and the standard deviation.

B.

It is necessary to assume the wait times at the lights are independent to calculate the standard deviation.

C.

It is necessary to assume the wait times at the lights are independent to calculate the mean.

D.

No assumptions are necessary.

2.

Suppose you want to estimate the proportion of traditional college students on your campus who own their own car. From research on other college campuses, you believe the proportion will be near

30%.

What sample size is needed if you wish to be

98%

confident that your estimate is within

0.02

of the true proportion?

A sample size of

enter your response here

is needed.

(Round up to the nearest whole number.)