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y is what percent of x?

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Source: — Problem Solving |

by Patrick_GMATFix » Mon Mar 10, 2014 5:54 pm
One approach is to plug in easy values that agree with the data given: "x is m percent of y" --> "1 is 20 percent of 5". Then solve; "y is what percent of x" --> "5 is what percent of 1?" The answer is 500; find it in the answer choices by replacing m with your plug-in value (m=20 in our case).

The answer is E. I go through the question in detail in the full solution below (taken from the GMATFix App).

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by Brent@GMATPrepNow » Mon Mar 10, 2014 7:26 pm
If m > 0 and x is m percent of y, then, in terms of m, y is what percent of x?

A. 100m
B. 1/(100m)
C. 1/m
D. 10/m
E. 10000/m
One approach is to plug in some numbers that meet the given condition.

x is m percent of y
How about 10 is 25 percent of 40
So, x = 10, m = 25 and y = 40
Great, so these values satisfy the given condition. Now onto . . .

in terms of m, y is what percent of x?
In other words, 40 is what percent of 10?
Well, 40 is 400 percent of 10

So, we need an answer choice that yields an output of 400, when m = 25. Let's plug 25 in for m . . .

A. 100(25) = 2500 NOPE
B. 1/[100(25)] = 1/2500 NOPE
C. 1/25 = 1/25 NOPE
D. 10/25 = 2/5 NOPE
E. 10000/25 = 400 BINGO!

Answer: E

Try plugging in your own set of values that meet the given condition.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by Abhishek009 » Wed Mar 12, 2014 10:06 am
LulaBrazilia wrote:If m > 0 and x is m percent of y
x = (m/100)y

x = my/100

y = 100x / m
LulaBrazilia wrote:in terms of m, y is what percent of x?
( y / x )* 100% is -

(100x / m)/x *100

(100x /m )(1/x) *100

(100 / m )100

10000/m %

Hence answer is definitely (E)
Abhishek
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by tushain » Tue Mar 18, 2014 4:29 am
x = y.m/100
y= x.100/m
let y be n% of x
y= x.n/100 = x.100/m
n= 100.100/m = 10000/m
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