A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that at least one of these is defective is
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Correct Answer: Option B
Explanation:
Probability( None is defective) \(=16 \mathrm{C} 2 / 20 \mathrm{C} 2=12 / 19\).
Probability (at least one is defective) \(=(1-12 / 19)=7 / 19\).
Probability( None is defective) \(=16 \mathrm{C} 2 / 20 \mathrm{C} 2=12 / 19\).
Probability (at least one is defective) \(=(1-12 / 19)=7 / 19\).