Final answer:
The speed of a person who runs 3 miles in 40 minutes is calculated by converting time to hours and dividing the distance by time, resulting in a speed of 4.5 mph.
Step-by-step explanation:
To calculate the speed in mph for a person who runs 3 miles in 40 minutes, you can use the formula for speed, which is distance divided by time. First, convert 40 minutes to hours, since the speed needs to be in miles per hour (mph).
There are 60 minutes in an hour, so 40 minutes is 40/60 hours, which simplifies to 2/3 hours. Now, divide the distance by the time to get the speed:
Speed = Distance ÷ Time = 3 miles ÷ (2/3) hours = 4.5 mph.
Therefore, the person's speed is 4.5 mph.
Considering that 40 percent of runners ran at speeds of 7.5 mph or less, a speed of 4.5 mph would place this person within that category, implying a relatively average running speed.