Freshman math question, super confused!

Today while Don was swimming, he started
wondering how many lengths he would have to swim in order to swim different distances. At one end of the pool, he stopped, gasping for breath, and asked the lifeguard. She told him that 1 length of the pool is 25 yards and that 72 lengths is 1 mile. As he continued swimming, he wondered:

a. Is 72 lengths really a mile? Exactly how many lengths would it take to swim a mile?

b. If it took him a total of 40 minutes to swim a mile, what was his average speed in feet per second?

c. How many lengths would it take to swim a kilometer?

d. Last summer Don got to swim in a pool that was 25 meters long. How many lengths would it take to swim a kilometer there? How many for a mile?

1 answer

a. well there are 1760 yards in a mile, so is 1760=25*72? No. 1760/25 = ?

b. 5280 ft / (40*60) s = 2.2 ft/s

c.1 km = 0.62 mile, so it would be 1760/25 * 0.62

d. 1km = 1000m, so it would be 1000/25 lengths. For a mile, it would be 1000/25 / 0.62