Math CentralQuandaries & Queries


Question from marylyne, a student:

suppose you are late for school and you drive from your house at a constant rate of 70 mph.when class is over, you drive home at a more leisurely 50mph. what is your average speed?


Average speed is total distance divided by total time. You don't know the distance from home to school so let it be d miles. You drive at 70 miles per hour which is 1/70 hours/mile. The distance you drive is d miles so it takes you d × 1/70 = d/70 hours to drive to school.

How long did it take you to drive home form school? What was your total time? What was the total distance? What was your average speed?


About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS