In a box containing 100 bulbs, 10 are defective. The probability that out of a sample of 5 bulbs, none is defective is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $(\frac{9}{10})^5$
Total bulbs $=100$
Defective bulbs $=10$
Good bulbs $=90$
Probability that one bulb is good
$=\frac{90}{100}=\frac{9}{10}$
Probability that all $5$ bulbs are good
$=\left(\frac{9}{10}\right)^5$
The required probability is $\left(\frac{9}{10}\right)^5$.