Source: Official Guide for GMAT Review 2016 Problem Solving; #11


If it is assumed that 60 percent of

If it is assumed that 60 percent of those who receive a questionnaire by mail will respond and 300 responses are needed, what is the minimum number of questionnaires that should be mailed?

3 Explanations


John Robertson

Idea: Percentages, simplify fractions before solving
Find: 60% of X IOT equal needed 300 responses, from X total
x/5=100 ....(I divided by 3 first bc 300/3 is quicker than 300x5 i think, and gets you to a simple 100xZ multiplication)
x=100*5=500, D

Dec 17, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Nice work, John! For this problem, we can find the number of questionnaires to send by finding for what number x, 60% = 300, the number of desired responses. Also, excellent job simplifying the calculation to do it in the most efficient way possible for you :) Thanks for sharing your solution!

Dec 19, 2016 • Reply


Sunita Dutta

I think, we can do the same using the basic method of calculating percentage. 60% of what will give 300, i,e. 60/100 of x =300 which gives x=500

Sep 28, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Yes, this is another way to solve this question and a very efficient way to arrive at the correct solution. Great job! And thanks for sharing your solution :)

Sep 29, 2016 • Reply


Osvaldo Hernandez

For this question I followed a very basic approach to solving it, as I have been out of practice for awhile, but still managed to get the right answer by multiplying by 10% and adding it.

First, I just went down the answer choices and divided them in half (50%). Then I would add the remaining 10% to that answer choice I cut in half that I got from keeping in mind that 10% of 100 is 10 to help me get a ball park idea.

a) 200 + 40 (40 is 10% of 400) = 240
b)210 +42= 252
c) 240 + 48= 288
d)250 + 50=300
e)300+ 60= 360

and got the answer D

Jul 27, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Thanks for sharing your solution, Osvaldo! Nice work solving for the correct answer :)

Aug 2, 2016 • 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 5.3 Problem Solving

Improve Your Score

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

Learn More About Magoosh

Share Post