You want to buy a microwave oven and will choose model A if tis repair cost are lower than model B's. You research the repair cost of 44 models A ovens and 53 model B ovens. The results of your research are at a = 0.01. Would you buy model A. Assume the samples are randomly selected and that the sample are independent.

Model A Model B
- -
X1 = 81 X2 = 90
S1 = 13.50 S2 = 25

a). What is the claim?
b). Find the critical values and identify the rejection regions.
c). Find the standardized test statistic Z=
d). Decide whether to reject or fail to reject the null