Hello!
To find the circumference of a circle you do [tex]2 \pi r[/tex] where r is the radius of the circle
So we do 2[tex] \pi 72[/tex]
Then we substitute pi for 3.14
2 * 3.14 * 72 = 452.16 yds
Then we multiply this by 5 since he runs 5 laps
Which gives us the answer of 2260.8 yds
Hope this helps!