Question

Box 1 contains 1000 bulbs of which 10% are defective. Box 2 contains 2000 bulbs of which
% are defective. Two bulbs are picked from a randomly selected box. (a) Find the probability
hat both bulbs are defective. (b) Assuming that both are defective, find the probability that
hey came from box 1.

Answer 1

Step-by-step explanation:

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.