Aluminum castings are processed in lots of five each.A sample of two castings is randomly selected from each lot for inspection.A particular lot contains one defective casting; and x is the number of defective castings in the sample.P(x=1)is _______.
A)0.2
B)0.4
C)0.6
D)0.8
E)1.0

Question

Quizplus · Accepted Answer

The probability of selecting 1 defective casting out of 2 samples when there is 1 defective in a lot of 5 is calculated by considering the combinations of picking 1 defective and 1 non-defective casting. There are 4 non-defective castings, so the probability is (4 choose 1) * (1 choose 1) / (5 choose 2) = 4/10 = 0.4.

Aluminum Castings Are Processed in Lots of Five Each