Last year Country X generated 3 times as many kilowatt-hours of

Question

Last year Country X generated 3 times as many kilowatt-hours of electricity as Country Y, but both countries generated the same amount of electricity from nuclear power plants. If Country X generated k percent of its electricity from nuclear power plants, what percent of Country Y's electricity was generated from nuclear power plants?

(A) \(\frac{k}{3}\)

(B) \(\frac{2k}{3}\)

(C) \(\frac{3k}{2}\)

(D) \(2k\)

(E) \(3k\)

Show Answer

Official Answer

E

(A)  \frac{k}{3}

(B)  \frac{2k}{3}

(C)  \frac{3k}{2}

(D)  2k

(E)  3k

MartyMurray · Accepted Answer

Last year Country X generated 3 times as many kilowatt-hours of electricity as Country Y, but both countries generated the same amount of electricity from nuclear power plants. If Country X generated k percent of its electricity from nuclear power plants, what percent of Country Y's electricity was generated from nuclear power plants?

(A) \(\frac{k}{3}\)

(B) \(\frac{2k}{3}\)

(C) \(\frac{3k}{2}\)

(D) \(2k\)

(E) \(3k\)

Show Answer

Official Answer

E

Let x be the number of kilowatt-hours generated by Country X and y be the number of kilowatt-hours generated by Country Y.

Country X generated 3 times as many kilowatt-hours of electricity as Country Y

x = 3y

Country X generated k percent of its electricity from nuclear power plants

k% of x =  \frac{k}{100}x

both countries generated the same amount of electricity from nuclear power plants

Since x = 3y,   \frac{k}{100}x = \frac{3k}{100}y .

Thus, the percentage of Country Y's electriciy that was generated from nuclear power plants is 3k.

(A)  \frac{k}{3}

(B)  \frac{2k}{3}

(C)  \frac{3k}{2}

(D)  2k

(E)  3k   
 Correct answer:  E

Alternative Approach

Use smart numbers.

x = 3y

So, let x = 300 and y = 100.

Let k = 20% of x.

20% of 300 = 60

Country Y generates the same amount from nuclear ower plants, so 60 also.

Thus, the percentage of Country Y's electriciy that was generated from nuclear power plants is 60/100 = 60%.

60% = 3 x 20% = 3k

So, the percentage of Country Y's electriciy that was generated from nuclear power plants is 3k.

Correct answer:  E

rahulyadav123 · Answer

Is this question a 600-650 level for gmat focus or gmatclassic

MartyMurray · Answer

It's from an official Focus Edition practice test. You can tell by checking the tag above the question, which in this case says "GMAT Prep (Focus)."

MBAToronto2024 · Answer

KarishmaB 
hmmmm...not following what's wrong here:
X: 250 50 (from nuclear) -> sum is 300
Y: 50 50 (from nuclear) -> sum is 100

k/100 * 300 = 50 
3k= 50 which is E. Is it a correct method or just a correct guess?

705in11112025 · Answer

it's just straight up 3k using the proportional relationship directly (3 times as many kilowatt-hours)

lily123400 · Answer

This is how I translated the problem:
Country X: 3Y energy, N from nuclear
Country Y: Y energy, N from nuclear

k/100 * (3Y) = N
x(what we are solving for) / 100 * Y = N

Set that equal:
k/100*3Y = x/100 * Y
and you get x = 3k

Last year Country X generated 3 times as many kilowatt-hours of

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