Question

Are the machine tools manufactured by A and B different with regard to how long they last?

	Company A	Company B
X̅ (X bar)	16.2 Weeks	15.9 Weeks
s	0.2 Weeks	0.2 Weeks
n	40	40

Test at 8% significance level

Answer 1

The null and alternate hypothesis are:
H0:
Ha:

The test statistic is given by:

Since this is a two-tailed test, so the critical values are given by:

and

Since the test statistic does not lie between these two values, so we have sufficient evidence to reject H0.

So, we reject H0 and say that i.e. yes, the machines are different with regard to how long they last.