If a is travelling at 120 mph and is one lap (3/4 mile) behind, and B is travelling 110 mph, how many laps will it take A to catch up?

Question

math word problem

 

Answer 1

10 mph difference

3/4 mile apart

3/4 divided by 10 = 3/40 = 0.075 hours to catch up

or 3/40)(60) = 4 1/2 minutes. 120 mph is 2 miles per minute. 4 1/2 x 2 = 9 miles

120 x 3/40 = 9 miles

9 divided by 3/4 = 9(4/3) = 12 laps

Answer 2

Hey Rosemary -- here's the "play-by-play": PRETEND "A" is 1 mile behind ... at 10 mph closing speed, one mile needs 1/10 of an hour to close ... 120 mph covers 240 "half-miles"/hr OR 480 "qtr-miles"/hr ... three (3) of these "qtr-miles" would be covered 160 times/hr ... 1/10 of an hr travels 16 laps when 1 mile behind ==> the 3/4 mile lag would take 12 laps to catch up ... Best wishes, ma'am :)

Answer 3

120t - .75 = 110t

 

120t - 110t = .75

 

10t = .75

 

divide both sides by 10:

 

t = .075 hours

 

.075 * 120 =  9 miles

 

since 1 lap is 3/4 mile, so, 9 miles divided by .75 mile per lap is 12 laps.