M7MBA wrote: ↑

Fri Jun 05, 2020 8:31 am

At Company \(R,\) the average (arithmetic mean) age of executive employees is 54 years old and the average age of non-executive employees is 34 years old. What is the average age of all the employees at Company \(R?\)

(1) There are 10 executive employees at Company \(R.\)
(2) The number of non-executive employees at Company \(R\) is four times the number of executive employees at Company \(R.\)

[spoiler]OA=B[/spoiler]

Source: Princeton Review

Let's take each statement one by one.

(1) There are 10 executive employees at Company \(R.\)

Since we do not know the number of non-executive employees, we can't get the answer. Insufficient.

(2) The number of non-executive employees at Company \(R\) is four times the number of executive employees at Company \(R.\)

Say there are 4x non-executive employees and x executive employees; thus,

Average age of all employees = (4x*34 + x*54)/5x = (x/x)*(4*34 + 54)/5 = (4*34 + 54)/5 = a unique value

Sufficient

The correct answer: B

Hope this helps!

-Jay
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