SOLUTION: It takes Mary 2 minutes to run a track. John can run 1 mi/hr faster than Mary and it takes him 1 minute 30 seconds to run the same track. How long is the track? I understand tha

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Question 461268: It takes Mary 2 minutes to run a track. John can run 1 mi/hr faster than Mary and it takes him 1 minute 30 seconds to run the same track. How long is the track?
I understand that I need to somehow encompass the formula: D= rt
Usually once I get the first few steps completed, the rest is downhill. However, I wasn't sure how to begin the problem. Thank you very much
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
It takes Mary 2 minutes to run a track. John can run 1 mi/hr faster than Mary and it takes him 1 minute 30 seconds to run the same track. How long is the track?
:
Convert 1 min 30 sec to 1.5 min
:
Find the speed of each person first
Let s = M's speed
then
(s+1) = J's speed
:
Write a distance equation Dist = speed * time
M's dist = J's dist
2s = 1.5(s+1)
2s = 1.5s + 1.5
2s - 1.5s = 1.5
.5s = 1.5
s = 1.5%2F.5
s = 3 mph is M's speed
:
Note that we did this using minutes, conversion to hrs (mph is used) would
effect both sides of the equation so we can ignore it.
:
Find the distance of the track, now we have to convert min to hrs and miles to feet.
2%2F60 * 3(5280) = 528 ft is the length of the track
:
Check this using J's time and speed (1 mph faster than M)
1.5%2F60 * 4(5280) = 528 ft also