Question

there were 18 boys and some girls in one class .average marks 12 of boy in an examination while girls were 14.if the total average was 13.1 . so was the total number of students in class?​

Answer 1

Answer:

average = sum of quantities ÷no of qualities Let no of girls be X

average of boys = 12=total marks of boys ÷ 18 (no of boys)

12×18= 216= total marks of boys

total marks of girls = 14×X(as mentioned above)

average marks of all students = 13.1 = (14X + 216)÷(X + 18)

If we solve for X we get X = 22

total no. of students = 22+ 18= 40