Practice!

Sample Problem

64 onions subscribe to magazines. 28 of them subscribe to Time, 41 subscribe to Reader’s Digest, and 20 subscribe to Elle. There are 10 onions who subscribe to both Time and Reader’s Digest, 12 onions who subscribe to both Time and Elle, and 12 onions who subscribe to both Reader’s Digest and Elle. How many onions subscribe to all 3 kinds of magazines?

 

Solution

Draw a Venn Diagram.

Onions that subscribe to Time but not Elle: 28 − 12 = 16.

Onions that subscribe to Reader’s Digest but not Time: 41 − 10 = 31

Onions that subscribe to Elle but not Reader’s Digest: 20 − 12 = 8

Onions that subscribe to none of the three: 16 + 31 + 8 = 55.

Onions that subscribe to all three: 64 − 55 = 9.