GMAT Club Around The World!!! In an office, there are three types of e

Average salary of

clerks - $ 3,000
managers - $6,000
executives - $ 10,000

We can use weighted average to find the ratio

\(\frac{Clerks }{ Manager }\) = \(\frac{Managers - Average }{ Average - Clerks }\)

\(\frac{Clerks }{ Manager }\) = \(\frac{ 6000 - 4000}{ 4000 - 3000 }\)

\(\frac{Clerks }{ Manager }\) = \(\frac{ 2 }{ 1 }\)

Similarly,

\(\frac{Clerks }{ Executives }\) = \(\frac{Executives - Average }{ Average - Clerks }\)

\(\frac{Clerks }{ Executives }\) = \(\frac{ 10000 - 5000}{ 5000 - 3000 }\)

\(\frac{Clerks }{ Executives }\) = \(\frac{ 5 }{ 2 }\)

Combined Ratio =

\(\frac{Clerks }{ Manager }\) = \(\frac{ 2 }{ 1 }\)

\(\frac{Clerks }{ Executives }\) = \(\frac{ 5 }{ 2 }\)

Clerks : Managers : Executives = 10 : 5 : 4

Correct answer is E.

You can also use the easy Plug-In method:

You want to find out c:m:e and have the terms

I) (3000c+6000m/(c+m)) = 4000
II) (3000c + 10000e/(c+e)) = 5000

Now, start with C. 10:4:3

Plug in 10 and 4 for c and m, respectively, into the first term I).

3000*10 + 6000*4 / (10 + 4) = 54,000 / 14.

You should see, that this does not equal 4000. Cross out C.

However, the answer was quite close (4000*14 = 56,000), so let´s move on with D, since there are similar numbers.

3000*10 + 6000*5 / (10 + 5) = 60,000 / 15 = 4000

Nice! This one fits. Now, we only have to try out whether the answer also fits into the second term II):

3000 * 10 + 10000*2 / (10 + 2) = 50,000 / 12 =/= 5000

--> Cross out D.

Now, since E is similar to D (c:m is the same), let´s try out E:

3000 * 10 + 10000 * 4 / (10 + 4) = 70,000 / 14 = 5,000

This is it! You have found the right answer: E.