Question

Suppose the average commute time of your employees is unknown. The standard deviation of their commute time is estimated as 22.8 minutes. How many employees must be included in a sample to create a 99 percent confidence interval for the average commute time with a confidence interval width of no more than 12 minutes

Answer 1

96 employees

Explanation:

Given that the standard deviation = 22.8

The width in the question = 12

We solve for the margin of error E.

E = width / 2

= 12/2 = 6

At 99%

Alpha = 1-0.99

= 0.01

Alpha/2 = 0.01/2 = 0.005

Z0.005 = 2.576

Sample size n

= ((2.576x22.8)/2)²

= 95.8

= 96

The number of employees is 96

Thank you!