Question

If you run for 0.4 hours at 7 mph, how fast should you walk during the next 0.8 hours to have the average speed of 5 mph?

Answer 1

4 miles per hour

Answer 2

4mph

0.4 x 7 mph =2.8 miles - distance run.

Let the required speed =S

[2.8 + 0.8S] / [0.4+0.8] =5, solve for S

S =4 mph - must walk to attain an average of 5 mph, or:

6 miles / 1.2 hours =5 mph