Question

A. Group of cross country runners decided to go on an hour and a half run. During the first hour, they ran a total of 13 kilometers. Then, they ran 5.0 kilometers during the next half an hour. What was the group's average speed for the entire run?

Answer 1

The average speed for the entire run is 12 km/h.

Explanation:

The average speed is given by the following equation:

`\overline{v} = (d_(T))/(t_(T))`

Where:

`d_(T)`: is the total distance

`t_(T)`: is the total time

If during the first hour, they ran a total of 13 kilometers and then, they ran 5.0 kilometers during the next half an hour we have:

`d_(T) = 13 km + 5 km = 18 km`

`t_(T) = 1 h + (1)/(2) h = 1.5 h`

Hence, the average speed is:

`\overline{v} = (d_(T))/(t_(T)) = (18 km)/(1.5 h) = 12 km/h`

Therefore, the average speed for the entire run is 12 km/h.

I hope it helps you!