If Charlie runs 3 yards per second and there are 3600 seconds in an hour, then he runs
3 * 3600 = 10800 yards per hour.
There are also 1760 yards in one mile, so we need to divide 10800 by 1760 to find out how many miles it is:
10800 ÷ 1760 =
= 6,136363636363636
I think we should round it:
6,136363636363636 ≈ 6,1
Answer: Charlie runs with a speed of about 6,1 miles per hour.
