1/(1+1/3) - 1/ (1+1/2) =
A) -1/3
B) -1/6
C) -1/12
D) 1/12
E) 1/3
OA: D
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OG2016 - fractions
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boomgoesthegmat
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USEFUL/IMPORTANT rule: 1/(a/b) = b/aboomgoesthegmat wrote:1/(1+1/3) - 1/ (1+1/2) =
A) -1/3
B) -1/6
C) -1/12
D) 1/12
E) 1/3
So, 1/(3/2) = 2/3
And 1/(5/6) = 6/5
etc...
Now onto the question....
1/(1 + 1/3) - 1/ (1+1/2) = 1/(4/3) - 1/ (3/2)
= 3/4 - 2/3
= 9/12 - 8/12
= 1/12
= D
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OptimusPrep
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Such questions might look intimidating at first, but if we solve one fraction at a time, we can easily solve themboomgoesthegmat wrote:1/(1+1/3) - 1/ (1+1/2) =
A) -1/3
B) -1/6
C) -1/12
D) 1/12
E) 1/3
OA: D
1/(1+1/3) - 1/ (1+1/2) = 1/(4/3) - 1/(3/2) = 3/4 - 2/3 = (9-8)/12 = 1/12
Correct option: D
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The first term can be simplified as: 1/(1 + 1/3) = 1/(4/3) = 3/4boomgoesthegmat wrote:1/(1+1/3) - 1/ (1+1/2) =
A) -1/3
B) -1/6
C) -1/12
D) 1/12
E) 1/3
The second term can be simplified as: 1/(1 + 1/2) = 1/(3/2) = 2/3
Thus, 3/4 - 2/3 = 9/12 - 8/12 = 1/12.
Answer: D
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Hi All,
We're asked for the value 1/(1+1/3) - 1/ (1+1/2). Most Test Takers would use standard Arithmetic to answer this question (which is fine). By 'converting' the fractions though, you can get the solution with a little logic and not that much math...
1/(1+1/3) = 1/1.333
1/ (1+1/2) = 1/1.5
The first fraction is BIGGER than the second fraction (because it has the smaller denominator). Since we're subtracting a smaller fraction from a larger fraction, we're looking for an answer that is POSITIVE. Since those fractions are fairly close to one another, the answer won't be that much bigger than 0. There's only one answer that matches.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
We're asked for the value 1/(1+1/3) - 1/ (1+1/2). Most Test Takers would use standard Arithmetic to answer this question (which is fine). By 'converting' the fractions though, you can get the solution with a little logic and not that much math...
1/(1+1/3) = 1/1.333
1/ (1+1/2) = 1/1.5
The first fraction is BIGGER than the second fraction (because it has the smaller denominator). Since we're subtracting a smaller fraction from a larger fraction, we're looking for an answer that is POSITIVE. Since those fractions are fairly close to one another, the answer won't be that much bigger than 0. There's only one answer that matches.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
