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
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Louise is three times as old as Mary. Mary is twice as
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Brent@GMATPrepNow
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GIVEN: Louise is L years oldM7MBA 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
Louise is three times as old as Mary
This also means that Mary is 1/3 as old as Louise
Louise's age = L
So, Mary's age = (1/3)L = L/3
Mary is twice as old as Natalie.
This also means that Natalie is 1/2 as old as Mary
Mary's age = L/3
So, Natalie's age = (1/2)(L/3) = L/6
What is the average (arithmetic mean) age of the three women, in terms of L?
Average age = (sum of all 3 ages)/3
Sum of all 3 ages = L + L/3 + L/6
= 6L/6 + 2L/6 + L/6
= 9L/6
= 3L/2
So, average age = (3L/2)/3
= L/2
Answer: B
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Brent
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Given, Louise is three times as old as MaryM7MBA 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
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
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Scott@TargetTestPrep
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Solution: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
We can let M and N be the ages of Mary and Natalie, respectively. Therefore, we have:
L = 3M
and
M = 2N
Since M = L/3 and N = M/2 = (L/3)/2 = L/6, the average age of the three women, in terms of L, is:
(L + L/3 + L/6)/3
Multiplying the expression by 6/6, we have:
(6L + 2L + L)/18
9L/18
L/2
Answer: B
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