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Source: Official Guide for the GMAT 13th Ed. Data Sufficiency; #41 Official Guide for the GMAT 2015 14th Ed. Data Sufficiency; #41


Is 4^(x+y) = 8^10?

Is 4^(x+y) = 8^10?

3 Explanations



Hey. If the Q asked for let's say individual values of x or y? then each statement alone should be sufficient? Right or still no?

May 22, 2018 • Comment

Sam Kinsman

Hi Jia,

Notice that the question is asking us whether it is true that 4^(x+y) = 8^10.

If, instead of asking us this, the question told us that the statement 4^(x+y) = 8^10 was true, and asked us to find the values of x and y, then yes: each statement would be sufficient by itself :)

May 24, 2018 • Reply


Gravatar Cydney Seigerman, Magoosh Tutor

Hi Jay :)

I totally understand your line of thinking, but we don't actually know that x+y = 15. Rather, we've rearranged the question to ask: Is x+y=15? For that reason, we cannot use the equation x+y=15 in combination with the two statements to solve for the two variables. Conversely, we need a system of equations that allows us to answer the question, "Is x+y=15?" For that reason, neither statement is sufficient alone but the two statements are sufficient together to answer the question.

I hope this helps!

Dec 30, 2015 • Comment


Gravatar Mike McGarry, Magoosh Tutor

Jan 3, 2014 • Comment


Hey Mike, I have doubt in this here can't the ans be D. Because here we have x+y=15. Now in statement 1 it is given x-y=9 and now by solving this and x+y=15 we get the values of x & y. Similarly for the statement 2 the same process done will give the values of x & y.

Dec 24, 2015 • Reply

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Section 6.3 Data Sufficiency

Section 6.3 Data Sufficiency

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