A College nursing student wants to estimate the number of times per year a middle aged woman visits a doctors office. He estimates that the population standard deviation of the number of visits is approximately four, and he wants the estimate to be within two times of the actual mean value. How large a sample should the nurse take to obtain a 90% confidence interval?

For part (a), use a positive critical value rounded to 3 decimal places.

(a) What is the critical value that will need to be used to calculate the sample size?

A is ______________

For part (b), round your answer UP to the nearest whole number.

(b) What is the sample size required?

B is _______________

Part 2:

In a time-use study, 62 randomly selected managers were found to spend a mean of 3.91 h each day on paperwork. The population standard deviation is known to be about 1.35 h. Construct the 90 % confidence interval for the mean time spent on paperwork by all managers.

Round thez-value to 3 decimal places and the confidence interval values to 2 decimal places.

For part (a), use a positivez-value.

(a) What is the criticalz-value that will need to be used to calculate the confidence interval?

_________________

(b) What is the 90% confidence interval?

__________ < __________