Math CentralQuandaries & Queries


Question from larisa, a parent:

One racer makes a complete trip around the track every 28 seconds, while the other racer completes a trip around the track every minute. How many times will the first racer pass the second racer in 30 minutes?


To solve problems of this sort (and "the one with the bathtub" and "the one with the lawnmowers" and many others) convert from time per unit of work to units of work per time. This typically lets cooperation be represented by addition and "working against each other" by subtraction.

Racer 1 completes 1/28 lap per second or _________ laps (in 30 min).

Racer 2 completes ________ lap per second or _________laps (in 30 min).

How many more complete laps does Racer 1 complete?

Good Hunting!


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