SSC CPO 2019 PYQ — Question 118

The average score of 42 students in a test is 69.

Now Sum of scores of all 42 students = Average × total number of students = 42 × 69 = 2898

The ratio of number of Boys to girls = 10 : 11

If boys are 10x then girls will be 11x

21x = 42

x = 2

So the number of boys = 20

Number of girls = 22

Let the average score of girls = y

So the average score of boys = y + (y × 20)/100 = 6y/5

Sum of scores of all 42 students = 22y + 20(6y/5) = 46y = 2898

46y = 2898

y = 63

So, the Average score of boys = (6/5) × 63 = 75.6