Circuit boards for wireless telephones are etched, in an acid bath, in batches of 100 boards.A sample of seven boards is randomly selected from each lot for inspection.A particular batch contains two defective boards; and x is the number of defective boards in the sample.P(x=2)is _______.
A)0.1315
B)0.8642
C)0.0042
D)0.6134
E)0.0034

Question

Quizplus · Accepted Answer

The probability of selecting exactly 2 defective boards out of 7 from a batch of 100 boards with 2 defective ones is calculated using the hypergeometric distribution formula. The probability P(x=2) is found by calculating the combination of choosing 2 defective out of 2 and 5 non-defective out of 98, divided by the combination of choosing 7 out of 100. This results in a very small probability, which matches closest to option C, 0.0042.

Circuit Boards for Wireless Telephones Are Etched, in an Acid