Wayne's Wheel
(page 144)

Here is a solution from Beverly Bogden's class, which appears to be in New Jersey...

Member's Names: Matt N, Lee O, Brent P, Jack A

Question of the task: What is the thickness of Wayne's wheel?

Our Answer: 12.6651478 cm

How we came up with our confident answer:

When Wayne's Wheel rolled forward four times, it covers a distance of ten meters. Therefore, it travels 2.5 meters per one rotation. The second clue stated that the circumference of the hub was the same as the diameter of the wheel. Then we concluded that the diameter of Wayne's wheel was 0.795774715 meters. We discovered this by dividing 2.5 (circumference) by Pi, getting the diameter. The next clue explained that the thickness of the wheel was the same as the radius of the hub. We took 0.795994715m and divided by Pi. The result was 0.12665148 meters, or 12.6651478 centimeters.

So I got this answer (I especially like "confident answer"!) but the thing that troubled me was the number of decimal places. So I wrote back: " My question is, how many decimal places do you think you're entitled to keep? Put differently, how many are practical?" And THEY wrote back:

Dear Tim,

Thank you for your e-mail. We want to keep 3. We think that 3 decimal places are practical for our answer.

Matt, Lee, Brent, and Jack

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