Question

The average score out of 100 of boys in an examination of a school is 71 and that of the girls is 73.The average score of the school examination is 71.8. Find the ratio of the boys to the number of girls that appeared in the examination.

Answer 1

Suppose no. of girls be x, and no. of boys be y..... 
total score = 71*y + 73*x 
total no. of students= x+y 
avg. school score = total score / total no. of students 
=> 71*y + 73*x / x+y =71.8 
=> 71*y + 73*x = 71.8(x+y) 
=>73*x - 71.8*x = 71.8*y-71*y 
=> 1.2*x= 0.8*y 
=> x / y = 0.8 / 1.2 
=> x / y = 2/3 

SO THE RATIO IS 2:3