Question

A simple random sample of 100 postal employees is used to test if the average time postal employees have worked for the postal service has changed from the value of 7.5 years recorded 20 years ago. The sample mean was 7 years with a standard deviation of s = 2 years. Assume the distribution of the time the employees have worked for the postal services is approximately normal.

What is the calculated value of “t” (Test Statistics)?

-0.4092

-2.50

5.681

-1.285

2.330

Answer 1

Solution :

This is the two tailed test .

The null and alternative hypothesis is ,

H0 :   =7.5

Ha : 7.5

Test statistic = t

= ( - ) / s / n

= (7-7.5) / 2/ 100

Test statistic = -2.50