In: Statistics and Probability
A batch of 10 discs has 3 defective discs. A sample of 5 discs is randomly selected from the batch.
A. Find the probability that exactly one disc in the sample is defective.
B. Find the probability that at least 4 discs in the sample are not defective.
This is a hypergeometric distribution.
N = 10
k = 3
n = 5
a) P(X = 1) = 3C1 * 7C4 / 10C5 = 3 * 35 / 252 = 0.4167
b) P(at least 4 not defective) = P(at most 1 is defective)
= P(X < 1)
= P(X = 0) + P(X = 1)
= [3C0 * 7C5 / 10C5] + [3C1 * 7C4 / 10C5]
= 0.5