# Algebra

posted by on .

HELP!!! Super confused. Here's the problem.

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?

• Algebra - ,

72 lengths of 25 yards = 1800 yards
1 mile = 1760 yards, so he swam farther than a mile

to swim a mile:
1760/25 = 70.4
So he would need about 70 1/2 length to swim a mile, (might as well finish the 71 st length)

b)
1 mile = 5280 ft
rate = 5280/(2400) ft/sec = 11/5 or 2.2 ft/sec

c) 1 km = appr 1093.6 yds
number of length fo r 1 km = 1093.6/25 = 43.7 lengths

d) number of lengths to swim 1 km in a 25 m pool
= 1000/25 = 40

to swim 1 mile in a 25 m pool (there are 1609.344 m in 1 mile)
= 1609.344 /25 = 64.37 lengths

(time to get rid of all that mile, yards, feet etc, and go metric)