Students at the Zoo

I saw the following problem in the "Ask Marilyn" column in Parade Magazine. It is a good example of problem solving involving groups:

Say 90 students go to a zoo. Three have a hot dog, soda, and Popsicle; 24 have a hot dog; five have a hot dog and soda; 33 have a soda; 10 have a soda and Popsicle; 38 have a Popsicle; eight have a Popsicle and hot dog. How many had nothing?

Try to answer this problem for yourself. Then, you can click here to see the solution and analysis.