A cylinder 90 cm high has a circumference of 24 cm. A string makes exactly 5 complete turns around the cylinder while each of its two ends touch the cylinder's top and bottom respectively.

How long is the string?

I like the elegant answer of 150, but if you took 5 wraps around the center of the cylinder and then run the ends straight  up and down to the top and bottom, you get (5 x 24) + 90 = 210. Minus a tiny error  due to the width of the string.

Posted by bob909 on 2004-09-13 03:08:21