10.7 You have been asked to determine if two different production processes have different mean numbers of units produced per hour. Process 1 has a mean defined as m1 and process 2 has a mean defined as m2.

The null and alternative hypotheses are as follows:

H0 : m1 - m2 … 0 H1 : m1 - m2 7 0 The process variances are unknown but assumed to be equal. Using random samples of 49 observations from Process 1 and 25 observations from Process 2, the sample means are 55 and 46 for populations 1 and 2, respectively. Can you reject the null hypothesis using a probability of Type I error a = 0.05 in each case?

a. The sample standard deviation from Process 1 is 28 and from Process 2 is 25.

b. The sample standard deviation from Process 1 is 20 and from Process 2 is 31.

c. The sample standard deviation from Process 1 is 28 and from Process 2 is 34.

d. The sample standard deviation from Process 1 is 17 and from Process 2 is 40.

Application Exercises