Bridge Collapsing Puzzle

[puzzle]

Hi,


A bridge will collapse in 17 minutes.

4 people want to cross it before it will collapse. It is a dark night and there is only one torch between them.

Only two people can cross at a time.

"A" takes a minute to cross.
"B" takes 2 minutes.
"C" takes 5
"D" takes 10 minutes

How do they all cross before the bridge collapses?

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[Math]

Solution:



A and B cross first using up 2 minutes.
A comes back making it 3
C and D cross making it 13 minutes
then B crosses back over making it 15 minutes.
And finally A and B cross together to make it 17 minutes!



Welcome to discuss your other solutions.