Transum Tunnel

A Maths Starter of The Day

Daniel, Anthony, Christopher and Joseph have to walk through a long dark tunnel. They only have one torch between them so a maximum of two people can go through the tunnel at any one time. Each person takes a different amount of time to get through the tunnel and if two people walk together they must walk at the rate of the slowest.

Daniel takes 2 minutes to walk through,
Anthony takes 3 minutes to walk through,
Christopher takes 6 minutes to walk through,
Joseph takes 7 minutes to walk through.

What is the least amount of time for all four to walk through the tunnel?

Notes:
1. All four begin at the same end of the tunnel.
2. The torch must be walked back through the tunnel by at least one person, it cannot be thrown.
3. The answer is less than 20 minutes!

Example:
If Christopher and Joseph walk through the tunnel together it will take 7 minutes, If Christopher then walks the torch back through the tunnel a total of 13 minutes will have passed. Continue till all four are at the other end of the tunnel.

 

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Wednesday, February 07, 2007

 

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Friday, February 08, 2008

 

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ANSWER

18 minutes:

Daniel and Anthony walk through taking 3 minutes
Daniel walks back with the torch taking 2 minutes [5 minutes total]
Christopher and Joseph walk through taking 7 minutes [12 minutes total]
Anthony walks back with the torch taking 3 minutes [15 minutes total]
Daniel and Anthony walk through taking 3 minutes [18 minutes total]
Teacher, do your students have one to one access to computers?

Whether your students each have a TabletPC or share a desktop PC, this activity lends itself to eLearning (Engaged Learning).

Here's the URL which will take
them to Tran Tunnels, a mathematical adventure.

http://www.transum.org/go/?to=Tunnels