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Paper Gmat Test-Tough Fraction

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by khurram » Wed Jun 04, 2008 12:24 pm
1/2^12 + 2/2^13+3/2^14+4/2^15

Ans is 1/2^10.

Any someone please work this out for me, this one looks easy. But, not sure what I am doing wrong.

thanks
Khurram

ans choices are 1/2^10, 1/2^12,15/2^15,2/2^10,23/2^16

solution says if we express the numerators are powers of 2, then we get 1/2^12+2/2^13+2^2/2^14+2^3/2^15

Yeah makes no sense.

Khurram
Last edited by khurram on Wed Jun 04, 2008 12:43 pm, edited 1 time in total.
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Source: — Problem Solving |

by Ian Stewart » Wed Jun 04, 2008 12:35 pm
Are you sure that's the right answer? It doesn't look right to me. Or are there brackets that should be in the question?
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by kishore » Wed Jun 04, 2008 12:36 pm
Thats not the right answer.....
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by ksh » Wed Jun 04, 2008 11:41 pm
If the interpretation is right, question stem is wrong. pl check
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by zacharyz » Thu Jun 05, 2008 3:59 am
As presented, I want to say that the answer should be 13 / 2^14

convert them all into 2/^15 (common denominator)

2^3/2^15 + 2^3 / 2^15 + 6 / 2^15 + 4 / 2^15
=
(8+8+6+4)/2^15 -combine under the common denominator
=
26 / 2^15 -adding all numerators, you get 26
=
(13 * 2) / 2^15 -factor 26 to find a factor of 2
=
13 / 2^14 -divide out the 2 from the top and bottom.
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