Using a 90​%confidence​ level, a governmental department would like to estimate the average weekly hours worked by private employees in the country who are adults. Assume the standard deviation for...

Using a 90​%confidence​ level, a governmental department would like to estimate the average weekly hours worked by private employees in the country who are adults. Assume the standard deviation for the number of hours worked is six hours. Determine the sample sizes needed to construct this confidence interval using the following margins of error.

a. 3 hours - a. The sample size needed is----

b.1 hour - b. The sample size needed is----

c. 15 minutes c. The sample size needed is----

​(Round up to the nearest​ integer.)