M7MBA wrote:Louise is three times as old as Mary. Mary is twice as old as Natalie. If Louise is L years old, what is the average (arithmetic mean) age of the three women, in terms of L?
(A) L/3
(B) L/2
(C) 2L/3
(D) L/4
(E) L/6
[spoiler]OA=B[/spoiler]
Source: Manhattan GMAT
Given, Louise is three times as old as Mary
let the age of Mary be M,
Then L=3M or \(M=\frac{L}{3}\)
Given, Mary is twice as old as Natalie
Or, M=2N or \(N=\frac{N}{2} = \frac{L}{6}\)
Average age of L,M, and N in terms of \(L=\frac{M+N+L}{3} = \frac{1}{3}\left(\frac{L}{3}+\frac{L}{6}+L\right) = \frac{L}{2}.\)
Therefore,
B
