Subject :IMO Class : Class 9
The average marks (out of 100) of boys and girls in an examination are 70 and 73 respectively. If the average marks of all the students in an examination is 71, then find the ratio of the number of boys to the number of girls.
(A) 1 : 3
(B) 2 : 1
(C) 1 : 2
(D) 3 : 1
Ans 1:
Class : Class 10
1:2
because
lets take no. of boys as x then 70x will be total marks of boys
lets take girls as y then 73y will be no of total marks of girls
then 71x+71y will be equal to the total marks of whole class
then we can say that
70x+73y=71x+71y
it gives us x=2y
so ratio will be 1:2