Q169
In a school with 600 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average of the school is 11 years 9 months, then the average the number of girls in the school is :
A.
150
AnswerB.
250
C.
350
D.
450
Answer: Option A
Solution
Answer: Option A
Solution:
Let the number of girls be xThen, number of boys = (600 - x)
Then,
= 11x + 12 (600 - x)
⇔ x = 7200 - 7050
⇔ x = 150