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, Magoosh Tutor

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

Add Your Explanation

You must have a Magoosh account in order to leave an explanation.

Learn More About Magoosh

Official GMAT Material

Official Guide for GMAT Review 2016

Official Guide for the GMAT 2015 14th Ed.

Official Guide for the GMAT 13th Ed.

Nova's GRE Prep

Official Guide for the GMAT 12th Ed.

Revised GRE PDF 2nd Ed.

Section 6.3 Data Sufficiency

Section 6.3 Data Sufficiency

Improve Your Score

Magoosh GMAT is an affordable online course for studying the GMAT.

Learn More About Magoosh

Share Post