SOLUTION: A box contains 12 light bulbs of which 5 are defective. All the bulbs look alike and have equal probability of being chosen. Three bulbs are picked up at random. What is the probab
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Question 1194843: A box contains 12 light bulbs of which 5 are defective. All the bulbs look alike and have equal probability of being chosen. Three bulbs are picked up at random. What is the probability that at least 2 are defective? Answer by ikleyn(52781) (Show Source):
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A box contains 12 light bulbs of which 5 are defective.
All the bulbs look alike and have equal probability of being chosen.
Three bulbs are picked up at random. What is the probability that at least 2 are defective?
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The number of selecting 3 light bulbs from 12 is = = 220.
It goes to the denominator of the probability as the size of the space events.
The number of selecting 2 or more defective choosing 3 bulbs from 12 is
+ = 10*7 + 10 = 80.
This number goes to the numerator of the probability as the size of favorable events.
So, the probability is P = = = . ANSWER
