In a class of 60, where girls are twice that of boys, Rohan ranked seventeenth from top. If there are 9 girls ahead of Rohan, how many boys are after him in rank?
Sol: Let the number of boys be x. Then, number of girls = 2 x ∴ x + 2 x = 60 or x = 20 So, number of boys = 20 and number of girls = 40 Number of students behind Rohan in rank = 60 – 17 = 43 Number of girls ahead of Rohan in rank = 9 Number of girls behind Rohan in rank = 40 – 9 = 31 ∴ Number of boys behind Rohan in rank = 43 – 31 = 12
