The average age of all the students in a class is 18 years. The average age of the boys in the class is 19 years, and that of the girls is 14 years. If the number of girls in the class is 30, then what is the number of boys in the class?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 120.
Let the number of boys = x
Total age of boys = 19x
Total age of girls = 14 × 30 = 420
Total age of class = 18(x + 30)
According to the question,
19x + 420 = 18(x + 30)
x = 120