M is a girl and has the same number of brothers as sisters. N is a boy and has twice as many sisters as brothers. Mand N are the children of Q. How many children does Q have?

A 2

B 3

C 5

D 7

Correct Answer: Option D

Let the number of male kids be x.

For M,

number of brothers = x

number of sisters = x

number of girl kid = x+1

For N,

number of male kid = x

number of brothers = x-1

number of sisters = 2(x-1)

now, A/Q,

x+1 + x = x + 2(x-1)

2x + 1 = x + 2x – 2

2x +x -2x =1+2

x = 3 number of male kid = 3

number of girl kid = 3 + 1 = 4

Total kids = 3 + 4 = 7