10.66 Two types of defects, A and B, are frequently seen in the output of a certain manufacturing process. Each item can be classified into one of the four classes AB, , , , where denotes the absence of the type-A defect. For 100 inspected items, the following frequencies were observed:

AB 48, 18, 21, 13 Test the hypothesis that the four categories, in the order listed, occur in the ratio 5:2:2:1. (Use

.)