RRB RPF RPSF SI and CONS Model Papers 10 with solutions

Question : 56 of 120

Marks: +1, -0

The average of marks scored by the students of a class is 68. The average of marks of the girls in the class is 80 and that of boys is 60. What is the percentage of boys in the class ?

Validate

Solution:

(2) Let the number of boys and girls in the class be x and y respectively.
∴ 60x + 80y = 68(x + y)
⇒ 60x + 80y = 68x + 68y
⇒ 8x = 12y
⇒ 2x = 3y ⇒ y =

2/3

x
∴ Required percentage

= {x}/{x+y} × 100= {x}/{x+ {2}/{3} x} ×100

= {3 x}/{3 x+2 x} × 100= {3}/{5} × 100=60

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