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?
A) 36 mi/h
B) 42 mi/h
C) 30 mi/h
D) 24 mi/h

Question

Quizplus · Accepted Answer

To average 21 mi/h over the race, the final speed must be such that the average of the initial (6 mi/h) and final speeds equals 21 mi/h. Using the formula for average speed (initial speed + final speed)/2 = average speed, we solve for the final speed: (6 + final speed)/2 = 21, leading to a final speed of 36 mi/h.

A Bicyclist Starts a Timed Race at 6