Question

A box contains $20$ electric bulbs, out of which $4$ are defective. One bulb is chosen at random from this box. The probability of getting a defective bulb is :

• A. $\frac{4}{5}$
• B. $\frac{1}{5}$
• C. $\frac{7}{20}$
• D. $\frac{11}{20}$

Answer 1

The correct option is B

$\frac{1}{5}$

Given

$Totalnumberofelectricbulbs=20$

$Numberofdefectivebulbs=4$

We need to find probability of getting a defective bulb, if one bulb is chosen randomly

$P=\frac{(Numberofdefectivebulbs)}{(Totalnumberofbulbs)}$

$P=\frac{4}{20}$

We get,

$P=\frac{1}{5}$

Therefore, the answer is $\frac{1}{5}$

So, the correct option is (B)