Q1. A mechanical shop uses produces parts using two machines. Quality control officer has expressed concern about the quality of the finished parts. Quality control investigation has revealed that the part made by the two machines is defective sometimes. The officer randomly sampled 35 units of the part from each machine. Of those produced by machine A, five were defective. Seven of the 35 sampled parts from machine B were defective.

A). The production manager is interested in estimating the difference in proportions of the populations of parts that are defective between machine A and B. From the sample information, computer a 98% confidence interval.

B). Test the hypothesis from the results obtained in part A for a hypothesized proportion difference of zero.