Quantitative Aptitude Ques 942

Question: A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that atleast one of these is defective, is

Options:

A) $ \frac{4}{19} $

B) $ \frac{7}{19} $

C) $ \frac{12}{19} $

D) $ \frac{21}{95} $

Show Answer

Answer:

Correct Answer: B

Solution:

  • P (None is defective) $ =\frac{{}^{16}C _2}{{}^{20}C _2}=\frac{12}{19} $ P (atleast one is defective) $ =( 1-\frac{12}{19} )=\frac{7}{19} $
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