Question

In an examination out of 480 students, 85% of the girls and 70% of the boys have passed.
How many boys appeared in the examination , if total pass percentage was 75% ?
A. 370
B. 340
C. 320
D. 360

Answer 1

Correct Answer - C
(c ) Total number of students =480
Perecentage of total students passed =75% of total students `=(75 xx 480)/(100)=360` students
Now , using the condition from the question ,
Let the number of boys be x .
Then , 70% of x +85% of (480-x)=360
`implies (75 xx x)/(100)+(85 xx (480-x))/(100)=360`
`implies 70x-85x+40800=36000`
`implies 40800-36000=85x-70x`
`implies 48000=15x implies x=(4800)/(15)=320`
`:.` There are 320 boys who appeared for the examination. By alligation method -

`:.` Girl and boys appeared in 1:2 ratio
`:.` Boys`=(480)/(3)xx2=320`