yogirb8801 wrote:
Lake A has a duck population of 30 females and 36 males. Lake B’s duck population consists of the same ratio of females to males. If 6 new female ducks are added to Lake B and no other ducks are added or removed, the new total duck population of Lake B could be which of the following?
A. 144
B. 105
C. 78
D. 51
E. 36
A. 144
B. 105
C. 78
D. 51
E. 36
The ratio of females to males in Lake B is 30:36 = 5:6 --> the total number of ducks in Lake B must be a multiple of (5+6)=11.
When 6 new female ducks are added to Lake B, the total number of ducks in Lake B must be a multiple of 11 plus 6.
Only 105 is a multiple of 11 plus 6: 9*11+6=105.
Answer: B.
Hope it's clear.