Question

Zip, Inc. manufactures Zip drives on two different manufacturing processes. Because the management of this company is interested in determining if process 1 takes less manufacturing time, they selected independent samples from each process. The results of the samples are shown below. Process 1 Process 2 Sample Size 27 22 Sample Mean (in minutes) 10 14 Sample Variance 16 25 At 95% confidence, test to determine if there is sufficient evidence to indicate that process 1 takes a significantly shorter time to manufacture the Zip drives. Show working

Answer 1

Ans:

pooled standard deviation=sqrt(((27-1)*16+(22-1)*25)/(27+22-2))=4.475

standard error for difference in means=4.475*sqrt((1/27)+(1/22))=1.285

Test statistic:

t=(10-14)/1.285

t=-3.11

df=27+22-2=47

p-value=tdist(3.11,47,1)=0.0016

As,p-value<0.05,we reject the null hypothesis.

There is sufficient evidence to conclude that process 1 takes a significantly shorter time to manufacture the Zip drives.