Take home pay

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by Brent@GMATPrepNow » Thu Dec 31, 2015 10:47 am
I think you forgot to add the question :-)
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by DavidG@VeritasPrep » Thu Dec 31, 2015 11:08 am
I suspect you're looking for this one: https://www.beatthegmat.com/take-home-pa ... 76551.html
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by Amrabdelnaby » Fri Jan 01, 2016 2:57 am
Yes I was :)

Thanks
DavidG@VeritasPrep wrote:I suspect you're looking for this one: https://www.beatthegmat.com/take-home-pa ... 76551.html

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by [email protected] » Fri Jan 01, 2016 9:53 am
Hi Amrabdelnaby,

We can solve this question with some algebra, but you have to be detailed with how you assign variables.

If...
X = the amount of money Alice EARNED per month
Y = the amount of money Alice SAVED per month
Y/X = the FRACTION of her paycheck she saved per month
then...
12Y = the amount of money Alice saved in ONE YEAR

Since the TOTAL amount saved = 3 times (what she DIDN'T save), we have this...
12Y = 3(X - Y)

Now, we can simplify:
12Y = 3X - 3Y
15Y = 3X
5Y = X
Y/X = 1/5

Final Answer: D

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by GMATGuruNY » Fri Jan 01, 2016 1:30 pm
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
Alternate approach:

Let the amount saved each month = $1.
Total saved for the entire year = 12*1 = $12.
Since the total saved for the entire year -- $12 -- is 3 times the total not saved each month, the total not saved each month = 12/3 = $4.
Thus, the total monthly pay = (total saved each month) + (total not saved each month) = 1+4 = $5.
Resulting fraction:
(total monthly savings)/(total monthly pay) = 1/5.

The correct answer is D.
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by Amrabdelnaby » Fri Jan 01, 2016 1:32 pm
Thanks for the explanation Rich.

I have a problem I need to ask you about.

Usually, if not always, when I solve maths problems, even those with high difficulty, I tend to find my way through much more easily when I am solving them casually than when I am doing a diagnostic test, to the extent that many of the questions that I do wrong in the diagnostic test, when I redo them without looking at the correct answer choices I get them right! I am not sure how I could get over this silly problem
[email protected] wrote:Hi Amrabdelnaby,

We can solve this question with some algebra, but you have to be detailed with how you assign variables.

If...
X = the amount of money Alice EARNED per month
Y = the amount of money Alice SAVED per month
Y/X = the FRACTION of her paycheck she saved per month
then...
12Y = the amount of money Alice saved in ONE YEAR

Since the TOTAL amount saved = 3 times (what she DIDN'T save), we have this...
12Y = 3(X - Y)

Now, we can simplify:
12Y = 3X - 3Y
15Y = 3X
5Y = X
Y/X = 1/5

Final Answer: D

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Rich

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by [email protected] » Sat Jan 02, 2016 10:29 am
Hi Amrabdelnaby,

On Test Day (or when taking a CAT), you essentially have 2 goals when dealing with any individual prompt:

1) Answer the question correctly (if possible), in a reasonable amount of time.
2) Make sure that you're working efficiently, so that you can comfortably work through the entire section (without having to rush through questions at the end).

If "your way" of working through the Quant section gets you a high Quant Scaled Score and doesn't cause any other 'issues', then feel free to use it. However, sometimes the ANSWERS provide a huge hint/clue as to how to go about solving the problem or a shortcut that you can use to avoid some of the work. As such, ignoring the answers could hinder your performance.

From a different perspective, this might also be about anxiety - you perform better when you're not having to think about the clock.

1) How have you scored on each of your practice CATs (including the Quant and Verbal Scaled Scores)?

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by Brent@GMATPrepNow » Sat Jan 02, 2016 1:17 pm
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
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,
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by Matt@VeritasPrep » Fri Jan 08, 2016 1:36 pm
Amrabdelnaby wrote:Thanks for the explanation Rich.

I have a problem I need to ask you about.

Usually, if not always, when I solve maths problems, even those with high difficulty, I tend to find my way through much more easily when I am solving them casually than when I am doing a diagnostic test, to the extent that many of the questions that I do wrong in the diagnostic test, when I redo them without looking at the correct answer choices I get them right! I am not sure how I could get over this silly problem
In my experience, when I'm trying to SOLVE and COMPUTE at the same time, I make a lot of sloppy computational errors. It seems to be something to do with working memory: it overloads the brain to be thinking of what to do conceptually while also crunching numbers. So my rule of thumb is to doublecheck my math after the conceptual work is over; way more often than I'd like to admit I find some sort of goofy math (2 + 2 = 22) that my mind told me was fine in the heat of chasing a solution.