QUESTION

# In a class of 50 students, $40%$ are girls. Find the number of girls and the number of boys in the class.

Hint: Use the fact that the value of $x%$ of ‘y’ is $\dfrac{xy}{100}$ to calculate the number of girls in the class. Subtract the number of girls from the total number of students to calculate the number of boys in the class.
We know that in a class of 50 students, $40%$ of them are girls. We have to calculate the number of boys and girls in the class.
To calculate the number of girls, we will use the fact that the value of $x%$ of ‘y’ is $\dfrac{xy}{100}$.
Substituting $x=40,y=50$ in the above formula, the number of girls is $=\dfrac{40\times 50}{100}$.
Simplifying the above expression, the number of girls is $=\dfrac{2000}{100}=20$.
Thus, the number of boys $=50-20=30$.
Note: We can also calculate the number of boys in the class by calculating the percentage of boys in the class. To calculate the percentage of boys in the class, subtract the percentage of girls in the class from 100. Then calculate the number of boys as we calculated the number of girls using the percentage formula. We can check if the calculated number of boys and girls is correct by multiplying the ratio of the number of girls to the number of students by 100 and verify if it is equal to $40%$ or not.