The ratio of the total number of students in school A to school B is 5:7. The number of boys in school A is 40% less than the number of boys in school
B. The number of girls in school B is 100 more than the number of girls in school
A. If the average number of students in schools A and B is 3600, find the difference between the number of boys and girls in school
A.

ATQ, Total students in schools A and B = 3600 * 2 = 7200 Total students in school A = 7200 * 5/12 = 3000 Total students in school B = 7200 – 3000 = 4200 Let the number of girls in schools A and B be x and (x + 100) respectively. 40% less ⇒ boys in A = 60% of boys in B Let the number of boys in school B be 5y. Then boys in school A = 5y * 60/100 = 3y So, x + 3y = 3000 ---(1) 5y + (x + 100) = 4200 x + 5y = 4100 ---(2) (2) – (1): (x + 5y) – (x + 3y) = 4100 – 3000 2y = 1100 y = 550 From (1): x + 3*550 = 3000 x + 1650 = 3000 x = 1350 Number of boys in school A = 3 * 550 = 1650 Number of girls in school A = 1350 Required difference = 1650 – 1350 = 300