How is the speed in miles per hour calculated from a test course of 400 ft completed in 65 seconds?

The calculation of speed in miles per hour begins with determining the speed in feet per second and then converting that value to miles per hour. To find the speed, you would divide the total distance traveled by the total time taken.

In this scenario, the distance traveled is 400 feet, and the time taken is 65 seconds. To calculate the speed in miles per hour, first, you find the speed in feet per second by dividing the distance by the time. This gives you the speed in feet per second:

Speed (ft/sec) = Distance (ft) ÷ Time (sec) = 400 ft ÷ 65 sec.

To convert feet per second to miles per hour, you multiply by 3600 (the number of seconds in an hour) and then divide by 5280 (the number of feet in a mile). Since 3600 seconds is equivalent to 60 minutes, the formula incorporates the conversion into one step.

Thus, using the simplified version of the calculation, you can take the formula:

Speed (mph) = (Distance (ft) ÷ Time (sec)) x (3600 sec/hr ÷ 5280 ft/mi).

This calculation leads directly to the answer found in the choice whose