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Monthly salary - MGMAT CAT 3

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by josh80 » Mon Dec 09, 2013 6:13 pm
For each month of a given year except December, a worker earned the same monthly salary and donated one-tenth of that salary to charity. In December, the worker earned N times his usual monthly salary and donated one-fifth of his earnings to charity. If the worker's charitable contributions totaled one-eighth of his earnings for the entire year, what is the value of N?


8/5

5/2

3

11/3

4
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Source: — Problem Solving |

by Uva@90 » Mon Dec 09, 2013 7:50 pm
josh80 wrote:For each month of a given year except December, a worker earned the same monthly salary and donated one-tenth of that salary to charity. In December, the worker earned N times his usual monthly salary and donated one-fifth of his earnings to charity. If the worker's charitable contributions totaled one-eighth of his earnings for the entire year, what is the value of N?


8/5

5/2

3

11/3

4
Hi Josh80,
Lets us assume his salary for all months other than December be 10,000

So, He donates 1/10 of his salary for all months other than Dec = 10,000/10 = 1000

His December Month salary is N times his normal salary = N*10,000
He donates 1/5 of his salary on Dec = N*10,000/5 = 2000*N

His Total salary for that year = 10,000*11 + 10,000*N = 10,000(11+N)
His total donation is 1000*11 + 2000*N = 1000(11+2N)


What question states is, he donated 1/8 of the total salary for that year,so,
1000(11+2N) = 1/8(10,000)(11+N)
Solve for N,
N = 11/3

Hence answer is D

Regards,
Uva.
Known is a drop Unknown is an Ocean
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by theCodeToGMAT » Mon Dec 09, 2013 10:06 pm
Take home = 9x/10; Donated = x/10

In december, Salary = NX
Donated = NX/5; Take Home = 4NX/5

NX/5 + 11x/10 = 1/8 (11x + NX)

(2NX + 11x)/10 = 1/8 (11x + NX)

16NX + 88x = 110X + 10NX

6NX = 22x

N = 11/3

Answer [spoiler]{D}[/spoiler]
R A H U L
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