kaplan #9

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kaplan #9

by magical cook » Wed Aug 22, 2007 5:13 pm
9) The average (arithmetic mean) of 3a + 4 and another number is 2a. What is the average of the other number and a?

1) 2a
2) a-4
3) a-2
4) a+2
5) a+4


Can anyone help? Correct answer will follow. :) thanks
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by ratindasgupta » Wed Aug 22, 2007 9:52 pm
Let the other number be x.

x + (3a + 4) = 4a

so x = a - 4

So average of (a - 4) and a = (2a - 4)/2 = a - 2