SOLUTION: A box of 30 flashbulbs contains 10 defective bulbs. A random sample of 2 is selected and tested. Let X be the random variable associated with the number of defective bulbs in the

Question 1150083: A box of 30 flashbulbs contains 10 defective bulbs. A random sample of 2 is selected and tested. Let X be the random variable associated with the number of defective bulbs in the sample.
(A) Find the probability distribution of X.
(B) Find the expected number of defective bulbs in the sample.
Answer by VFBundy(438) (Show Source): You can put this solution on YOUR website!
Part (A):

Probability of 2 defective bulbs in the sample: = 9/87...(can be reduced to 3/29)
Probability of 1 defective bulb in the sample: = 40/87
Probability of 0 defective bulbs in the sample: = 38/87

Part (B):

2 * 9/87 = 18/87
1 * 40/87 = 40/87
0 * 38/87 = 0

18/87 + 40/87 + 0 = 58/87 = 2/3

The number of expected defective bulbs in the sample is 2/3...or, 0.6667.
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