Jar Y has 10% more marbles than Jar X . What percent of marbles from

No; the choices will be approximated only when GMAT question explicitly mentions that;

Here the answer is very close 4.54, not 5.


Jar Y has 10% more marbles than X
Y = 1.1X
If k marbles are taken out of Y. The remaining marbles in Jar Y= 1.1X-k
If k marbles are added to X. The new marbles' count in Jar X= X+k

And we know they are equal;

X+k = 1.1X-k
2k = 0.1X
k= 0.05X

The marbles taken out of Y = 0.05X
Question is: 0.05X is what percent of marbles that was originally there in Y i.e. 1.1X

\(\frac{0.05X}{1.1X}*100\)

\(\frac{0.05X}{1.1X}*100\)

\(\frac{50}{11} = 4.\bar{54} \approx 4.54\)

Sol: "A"

thanks fluke for the explanation

I did with number plugging as well
X=100
Y=110
we need to move 5 from Y.
5/110 = 1/22
1/22 < 1/20 which is 5%
only A is less than 5%.

Hi,

it is true that the exam will give you approximations for the anser choices (most of the times), but here it is a different story. We have to to move 5 marbles from y to x if we assume that x is 100 and hence, y is 110. But the question asks for the percantage of marbles that have to be removed from y! So even with our numbers 5/110= 4.54%.

I tried to attempt the question the same way as fluke did, but than I had a look at the anser choices and given the high differences amongs them answer A was clear without further calculations. If we know the difference between both jars is 10% and we want to level them we intuitively have to take half of the excess marbles (actually a little less than half, because a reduction in percentage is gigher than a percentage increase with the same amounts)

Therefore, we are looking for a percentage that is slightly below 5% (half of 10%), and given the wide spread of possible answer choices there is only one that is even close to 5%.

We can pick a convenient number, such as 100, to make this problem easier to solve. Let the number of marbles in Jar X = 100, and since Jar Y has 10% more marbles than Jar X, Jar Y has 1.1 x 100 = 110 marbles.

Thus, in order for the two jars to have an equal number of marbles, 5 marbles would need to be moved from Jar Y to Jar X so that each jar would have 105 (i.e., the same number of) marbles.

Now, we need to determine what percent 5 is of 110:

5/110 x 100 = 500/110 = 4.54 percent

Answer: A