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please help me attack this question
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Brent@GMATPrepNow
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Here's an algebraic approach.Alice's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save. If all money she saved lasr year was from her take-home pay, what fraction of her pay did she save each month?
a)1/2
b)1/3
c)1/4
d)1/5
e)1/6
Let M = Alice's monthly take home pay
Let f = the fraction we'll use to calculate monthly savings
The means that fM = the amount of $ Alice saves each month.
And this means that her annual savings = 12fM
Important: If f = the fraction used to calculate monthly savings, then 1-f = the fraction used to calculate amount not saved
The means that (1-f)M = the amount of $ Alice does not save each month.
Now we're ready to write an equation.
The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save.
We get: 12fM = 3(1-f)M
Now solve for f
Expand to get: 12fM = 3M - 3fM
Simplify: 15fM = 3M
Divide both sides by 15M to get: f = 3M/15M = [spoiler]1/5 = D[/spoiler]
Cheers,
Brent
Last edited by Brent@GMATPrepNow on Wed Jun 17, 2015 9:27 am, edited 1 time in total.
Brent Hanneson - Creator of GMATPrepNow.com
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Hi rodior,
This question shows up in this Forum every few months. Here was a discussion of the question (along with a variety of approaches to solving it):
https://www.beatthegmat.com/word-problems-t270244.html
GMAT assassins aren't born, they're made,
Rich
This question shows up in this Forum every few months. Here was a discussion of the question (along with a variety of approaches to solving it):
https://www.beatthegmat.com/word-problems-t270244.html
GMAT assassins aren't born, they're made,
Rich
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regor60
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Brent@GMATPrepNow wrote:The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save.Alice's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she saved at the end of the year was 3 times the amount of her take-home pay that she didn't save. If all money she saved lasr year was from her take-home pay, what fraction of her pay did she save each month?
a)1/2
b)1/3
c)1/4
d)1/5
e)1/6
Your interpretation adds the word "monthly" that doesn't exist in the original question. Without it and assuming annual take home pay not saved, I believe the answer would be 75%.
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Brent@GMATPrepNow
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Hi regor60,
That was a bad transcription on my part. I've added the missing words.
The original question reads...
The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save.
Cheers,
Brent
That was a bad transcription on my part. I've added the missing words.
The original question reads...
The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take home pay that she did not save.
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
