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If the average of 2x and 4x is 12, then x

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by Brent@GMATPrepNow » Fri Apr 27, 2018 5:43 am
VJesus12 wrote:If the average of 2x and 4x is 12, then x =

(A) 1
(B) 2
(C) 3
(D) 4
(E) 24
Given: the average of 2x and 4x is 12
We can write: (2x + 4x)/2 = 12
Simplify: 6x/2 = 12
Simplify: 3x = 12
Solve: x = 4

Answer: D

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by Vincen » Fri Apr 27, 2018 6:50 am
Hi vjesus12.

The average is the sum of each value divided by the total number of values. Here we have 2x and 4x, then we have 2 values.

Now, we know that the average is 12, this implies that $$12=\frac{2x+4x}{2}\ =\ \frac{6x}{2}=3x\ \Leftrightarrow\ \ x=\frac{12}{3}=4.$$ Then, the correct answer is the option D.

I hope this answer may help you.
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by [email protected] » Fri Apr 27, 2018 5:39 pm
Hi VJesus12,

We're told that the average of 2X and 4X is 12. We're asked for the value of X. This question can be solved Algebraically or by TESTing THE ANSWERS.

Since we have two different 'terms' - and an average of 12 - we know that one term is smaller than 12 and the other is bigger than 12. Based on the answers, we need 4X to be BIGGER than 12. Let's TEST Answer D...

Answer D: 4
IF.... X=4, then the two terms are 8 and 16.
The average would be (8+16)/2 = 24/2 = 12
This is an exact match for what we were told, so this MUST be the answer.

Final Answer: D

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by Scott@TargetTestPrep » Mon Apr 30, 2018 3:41 pm
VJesus12 wrote:If the average of 2x and 4x is 12, then x =

(A) 1
(B) 2
(C) 3
(D) 4
(E) 24
We can create the equation:

(2x + 4x)/2 = 12

6x/2 = 12

6x = 24

x = 4

Answer: D

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