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Mel9231
06-11-2009, 04:10 PM
I need help with the following problem. Mike can finish the track in 60 minutes. John is running on the same track in the opposite direction. They start at the same location and will meet every 15 minutes. How much time does John need to finish the track by himself? I believe the part about meeting every 15 minutes is important in solving the equation, but I do not know how to set it up or solve it. Thanks!

galactus
06-11-2009, 06:10 PM
Draw a picture of the circular track. Since it takes Mike 60 minutes to run one lap, he runs 1/4th the total distance around the track in 15 minutes.

John has met him, so he must have ran 3/4 of the way around the other way. Now see?. How much longer for John to make that extra 1/4th?.

Mel9231
06-11-2009, 10:13 PM
Is the answer 5 minutes? It seems that John can run the whole track in 20 minutes. If this is correct, I answered it logically without using algebra.

Denis
06-11-2009, 11:33 PM
It takes Mike 60 minutes to paint a wall.
It takes Mike and John working together 15 minutes to paint the same wall.

Get my drift?

Subhotosh Khan
06-12-2009, 08:03 AM
I need help with the following problem. Mike can finish the track in 60 minutes. John is running on the same track in the opposite direction. They start at the same location and will meet every 15 minutes. How much time does John need to finish the track by himself? I believe the part about meeting every 15 minutes is important in solving the equation, but I do not know how to set it up or solve it. Thanks!


Is the answer 5 minutes?

It seems that John can run the whole track in 20 minutes.

If this is correct, I answered it logically without using algebra.

What did you put down as answer - 5 minutes or 20 minutes?

Mel9231
06-12-2009, 11:56 PM
20 minutes

Subhotosh Khan
06-13-2009, 12:50 PM
20 minutes <<< Excellent

galactus
06-13-2009, 02:39 PM
If you want to set it up algebraically, you can do as Denis suggested.

\frac{1}{15}-\frac{1}{60}=\frac{1}{t}