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GRE Math Challenge #11- If a + 2b= 14 and 5a + 4b =16
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07 Sep 2014, 06:54
07 Sep 2014, 06:54
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Question Stats:
92% (00:59) correct
7% (02:49) wrong based on 26 sessions
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GRE Math Challenge #11- If a + 2b= 14 and 5a + 4b =16
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01 Sep 2017, 13:44
01 Sep 2017, 13:44
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sandy wrote:
The average (arithmetic mean) of a and b = (a + b)/2
The slow approach to answer this question is to solve the system of equations to find the individual values of a and b.
The fast approach is to recognize that we need only find the SUM of a and b
Here's what I mean...
Given:
a + 2b = 14
5a + 4b =16
ADD the two equations to get:
6a + 6b = 30
Factor to get:
6(a + b) = 30
Divide both sides by 6 to get:
a + b = 5
Divide both sides by 2 to get:
(a + b)/2 = 5/2
Perfect!
The average (arithmetic mean) of a and b = (a + b)/2, and we can see that (a + b)/2 = 5/2
Answer: 5/2
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Re: GRE Math Challenge #11- If a + 2b= 14 and 5a + 4b =16
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12 Jul 2024, 15:43
12 Jul 2024, 15:43
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