A runner wants to run 11.8 km. Her running pace is 7.4 mi/hr. How many minutes must she run? Express your answer using two significant figures.

She must run 59 min to run 11.8 km.

Explanation:

Hi there!

First let's convert mi/h into km/min:

7.4 mi/h · (1.61 km / 1 mi) · (1 h / 60 min) = 0.20 km/min (notice how the units mi and h cancel).

The runner runs at 0.20 km / min, i. e., every minute she travels 0.20 km.

If 0.20 km are traveled in 1 min, then 11.8 km will be traveled in:

11.8 km / 0.20 km/min = 59 min

She must run 59 min to run 11.8 km.