In a box containing 100 bulbs, 10 are defective. Then the probability, that out of a sample of 5 bulbs none is defective, is:
Answer & explanation
Correct answer: option 3
$D$ → defective blub
$\bar D$ → Bulb is not defective
$P(D) = \frac{10}{100}=\frac{1}{10}$
$P(\bar D) =1- P(D) =\frac{9}{10}$
For 5 blubs P(none is defective) = ${^5C}_5(P(\bar D))^5$
$=\frac{9^5}{10^5}$