Percentages

[gmatstudent]

At Daifu university, 40% of all students are both members of a student organization and want to reduce their tuition costs. 20% of those students who want to reduce tuition are not members of the student organization. What percentage of all Daifu students want to reduce tuition?


* 20%
* 30%
* 40%
* 50%
* 60%

[RonPurewal]

please give the source of this problem. if you don't give the source within the next few days, then unfortunately, we'll have to delete the problem.

thanks

[gmatstudent]

The source is above

[RonPurewal]

use a double set matrix. the key is the realization that the 40% is an absolute percentage, but the 20% is a percentage OF a different quantity in the problem (read it carefully!). you can set the total to 100, because there's no indication of the total number of students.