Question

A lot of $20$ bulbs contains $4$ defective ones. One bulb is drawn at random from the lot. What is the probability that this bulb is defective?

• A. $\frac{1}{6}$
• B. $\frac{1}{5}$
• C. $\frac{1}{2}$
• D. $\frac{1}{3}$

Answer 1

Answer: (B)

$\frac{1}{5}$

Number of defective bulbs $=4$
Number of good bulbs (Not defective) $=16$
Total number of bulbs $=4+16=20$
Probability of getting a defective bulb $=\frac{4}{20}=\frac{1}{5}$