Here is the problem:

A bicyclist starts a timed race at 6.0 mi/h. In order to win, he must average 21 mi/h. Assuming constant acceleration from the start, how fast must he be traveling at the end of the race?

The answer is 36 mi/h, not 48 mi/h as I answered. Is there a graphical method to this one or am I missing a direct formula method?

Please help and thanks,

B