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A box contains 5 detective and 15 non-detective bulbs. Two bulbs are chosen at random. Find the probability that both the bulbs are non-defective.

A box contains 5 detective and 15 non-detective bulbs. Two bulbs are chosen at random. Find the probability that both the bulbs are non-defective. Correct Answer 21\/38

n(S) = C220 = 190 

n(E) = C215 = 105 

Therefore, P(E) = 105/190 = 21/38

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