Question

A world-class marathoner runs at 11.5 mph (miles per hour). Is this greater than 20 km/h?

a. -11.5 mph is equivalent to 7.15 km/h, so it is NOT greater than 20.
b. -11.5 mph is equivalent to 23.0 km/h, so this is greater than 20.
c. -11.5 mph is equivalent to 18.5 km/h—therefore it is NOT greater than 20.
d. -11.5 mph is exactly equal to 20.0 km/h.

Answer 1

After converting 11.5 mph to km/h, it is found to be equivalent to 18.5 km/h, which is not greater than 20 km/h.

Step-by-step explanation:

To determine whether 11.5 mph is greater than 20 km/h, we must convert miles per hour to kilometers per hour. There are 1.60934 kilometers in a mile, so we multiply the speed in mph by this conversion factor to find the equivalent speed in km/h.

11.5 mph × 1.60934 km/mi = 18.50741 km/h.

Comparing this to 20 km/h, we find that 11.5 mph is not greater than 20 km/h. Therefore, the correct answer choice is:

c. 11.5 mph is equivalent to 18.5 km/h—therefore it is NOT greater than 20.