SOLUTION: Box 1 contains 1000 bulbs of which 10% are defective. Box 2 contains 2000 bulbs of which 5% are defective. Two bulbs are picked from a randomly selected box. (a) Find the probabil

Question 374065: Box 1 contains 1000 bulbs of which 10% are defective. Box 2 contains 2000 bulbs of which 5% are defective. Two bulbs are picked from a randomly selected box.
(a) Find the probability that both bulbs are defective.
(b) Assuming that both are defective, find the probability that they came from box 1.
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
a)
There is a 0.5 probability that Box 1 is selected: 100/1000 * 99/999 = .00991
There is a 0.5 probability that Box 2 is selected: 100/2000 * 99/1999 = .00248
.
b)
.00991/(.00991+.00248)
=.00991/.01239 (rounding error)
=.800 the probability that they came from box 1.
.
Ed
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