Question

A teacher chooses a student at random from a class of $20$ boys. What is the probability that the student chosen is a boy?

• A. $1$
• B. $\frac{1}{20}$
  
• C. $20$
• D. $0$

Answer 1

The correct option is A $1$

There are $\text{20}$ boys in the class.

Let $\text{P(B)}$ denotes the probability of choosing a student that is a boy.

$\text{P(B)}=\frac{\text{Number of favourable outcomes}}{\text{Total number of outcomes}}$

In this case,
Number of favourable outcomes $=20$
Total number of outcomes $\text{= 20}$

$\text{P(B)}=\frac{20}{20}$

$\text{P(B)}=1$

Choosing a boy from a class of $\text{20}$ boys is a certain event as class consists of only boys. This is a case of "$\text{Certain Event}$".

$\therefore$ Option (a.) is the correct answer.