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

Answer:

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

Explanation:      

The average speed is given by the following equation:

$\overline{v} = \frac{d_{T}}{t_{T}}$

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:

$d_{T} = 13 km + 5 km = 18 km$

$t_{T} = 1 h + \frac{1}{2} h = 1.5 h$

Hence, the average speed is:

$\overline{v} = \frac{d_{T}}{t_{T}} = \frac{18 km}{1.5 h} = 12 km/h$

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

I hope it helps you!