A drapery store manager was interested in determining whether a new employee can install vertical blinds faster than an employee who has been with the company for two years. The manager takes independent samples of 10 vertical blind installations of each of the two employees and computes the following information.
New Employee Veteran Employee
Sample Size 10 10
Sample Mean 22.2 min 4.8 min
Standard Deviation 0.90 min .75 min
using the null and alternate hypothesis:
H0: mu1-mu2=0 vs. Ha: mu1-mu2 <0
The test statistic is -7.018
Alpha 0.05
What is the appropriate rejection region for this hypothesis test?
A) Reject H0 if t< -t_(alpha = 0.025, df = 19)
B) Reject H0 if t< -t_(alpha = 0.05, df = 18)
C) Reject H0 if t< -t_(alpha = 0.025, df = 18)
D) Reject H0 if t< -t_(alpha = 0.05, df = 19)