Math Quiz: NYT Learning Network

Through Math for America, I am part of an on-going collaboration with the New York Times Learning Network.  My latest contribution, a Test Yourself quiz-question, can be found here:

https://learning.blogs.nytimes.com/2011/09/07/test-yourself-math-sept-7-2011/

This question comes from an article about the proliferation of expensive summer camps catering to wealthy clientele.  How much does a day of high-end summer camp cost?