GRADE  9-12 / Age 14+

The Three Challenges

1.  Assume you keep all your socks in a drawer and when you dress, you remove a pair at random.  If you have four pairs of socks-one black, one white, one red and one blue-how many days per week on average will you be found wearing a matching pair?

2.  Find an English word in which the vowels a, e, i, o, and u and the semivowel y all appear in the right order.

3.  Jumblium is an interesting metal because it shrinks when heated and expands on cooling. Most metas, like iron, do the opposite.  Sandra knew this, so when Sherry asked her to heat an iron washer and cool a jumblium washer, she already had a good idea of what would happen to the size of the holes in the washers.  What does happen to them?


Be sure to use your MathWorld Interactive six problem-solving steps. Have fun!

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