At McLeod University, thirty percent of the students are in Engineering. Forty percent of Engineering students study Probabilistic Systems, and sixty percent of the students studying Probabilistic Systems are in Engineering. What percentage of students at McLeod are either in Engineering or studying Probabilistic Systems?

Question

At McLeod University, thirty percent of the students are in Engineering.   Forty percent of Engineering students study Probabilistic Systems, and sixty percent of the students studying Probabilistic Systems are in Engineering.  What percentage of students at McLeod are either in Engineering or studying Probabilistic Systems?

Steve · Answer

If you draw two intersecting circles, E and P, then the intersection is for students in both E and P.

E = .3S

The intersection of P&E = .4E = .6P
But, that means that .12S = .6P, so P = .2S

Add up E & P to get .5S = 50%