Crossing The Bridge Puzzle

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Crossing The Bridge Puzzle

Crossing The Bridge

Question:

Four people need to cross a  bridge at night which is likely to collapse. Unfortunately, they have only one torch and the bridge is too insecure to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

Before looking at the answer We Strongly advised you to think about the solution and take out the answer and then match your answer with ours. 

Answer:

17 min

First 1 and 2 goes    -   time taken 2 mins

1 comes back          -    time taken 1 mins

now 

7 and 10 goes          -    time taken 10 mins

2 comes back          -    time taken 2 mins

1 and goes               -    time taken 2 mins

Total time taken      -  2+1+10+2+2   = 17 min