Numb3rs, Season Six — and the Unexpected Quiz

On the other hand, the season opener of Numb3rs — Season Six, which is hard to believe! — was pretty good, even it was skimpy on the math and a bit long on tensions between Charlie and Amita. But this is television, after all.

Math content included Fibonacci spirals in nature, and the Unexpected Hanging paradox in its original form. In order to make the latter less gruesome and more relevant to students, it is usually changed to an unexpected quiz, as Jim Loy points out in the linked article. It goes something like this:

I’m going to give you a pop quiz next week, and I guarantee that it will come as a surprise to you. Of course I can’t give it on Friday, since if you walk into class on Friday and haven’t had the quiz yet, it will no longer be a surprise. So you rule out Friday.

Could I give it Thursday? Since you’ve already ruled out Friday, you will expect the pop quiz when you walk into class on Thursday. Then it won’t be a surprise. So I can’t give it Thursday.

By the same reasoning, I can’t give it Wednesday. Similarly, I can’t give it Tuesday. Or even Monday!

So, I guess I’ll just have to give the quiz right now.

And I hand out the quiz.

Where’s the flaw?

Categories: Math, Movies & (occasionally) TV, Teaching & Learning