In a certain school, 20% of students are below 8 years of age. The number of students above 8 years of age is $ \dfrac{2}{3} $ of the number of students of 8 years of age which is 48. What is the total number of students in the school?
72
80
120
100
Explanation:
Let the number of students be $ x $. Then,
Number of students above 8 years of age = (100 - 20)% of $ x $ = 80% of $ x $.
$\therefore$ 80% of $ x $ = 48 +$ \dfrac{2}{3} $of 48
$\Rightarrow \dfrac{80}{100} x $ = 80
$\Rightarrow x $ = 100.