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:

http://learning.blogs.nytimes.com/2011/04/27/test-yourself-math-april-27-2011/

This question is based on the increasing radius of evacuation around the Fukushima Daiichi Nuclear Plant, in the wake of the recent earthquake in Japan.