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Crossing the Bridge Puzzle
Crossing the Bridge
In Crossing the Bridge Puzzle, 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 minutes and “D” takes 10 minutes. How do they all cross before the bridge cross ?
Crossing the Bridge
In Crossing the Bridge Puzzle, 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 minutes and “D” takes 10 minutes. How do they all cross before the bridge cross ?
Solution
Here we have provided information for solution of Crossing the Bridge Puzzle :
Time in which bridge will collapse = 17 mins
Number of people wants to cross the bridge = 4 people
Number of torch they have = 1
Time take by A to cross the bridge = 1 minute
Time taken by B to cross the bridge = 2 minutes
Time taken by C to cross the bridge = 5 minutes
Time taken by D to cross the bridge = 10 minutes
Move Time
A & B Cross with torch 2 min
A return with torch 1 min
C & D Cross with torch 10 min
B return with torch 2 min
A & B cross with torch 2 minTotal time 17 min
Detail Analysis
A & B crosses the bridge in 2 mins and returns with the torch in 1 mins, so total time taken by now is 3 min.
Time left before the bridge collapse = 14 mins
C & D crosses the bridge in 10 mins and B returns with the torch in 2 mins, so total time taken by now is 15 min.
Time left before the bridge collapse = 2mins
Now, A & B were only left out and time left before the bridge collapse in 2 min but the maximum time taken by A & B to cross the bridge is 2 mins as time taken by A is 1 min and by B is 2 mins.
Hence A, B, C and D all four will cross the bridge within 17 mins.
Solution
Here we have provided information for solution of Crossing the Bridge Puzzle :
Time in which bridge will collapse = 17 mins
Number of people wants to cross the bridge = 4 people
Number of torch they have = 1
Time take by A to cross the bridge = 1 minute
Time taken by B to cross the bridge = 2 minutes
Time taken by C to cross the bridge = 5 minutes
Time taken by D to cross the bridge = 10 minutes
Move Time
A & B Cross with torch 2 min
A return with torch 1 min
C & D Cross with torch 10 min
B return with torch 2 min
A & B cross with torch 2 minTotal time 17 min
Detail Analysis
A & B crosses the bridge in 2 mins and returns with the torch in 1 mins, so total time taken by now is 3 min.
Time left before the bridge collapse = 14 mins
C & D crosses the bridge in 10 mins and B returns with the torch in 2 mins, so total time taken by now is 15 min.
Time left before the bridge collapse = 2mins
Now, A & B were only left out and time left before the bridge collapse in 2 min but the maximum time taken by A & B to cross the bridge is 2 mins as time taken by A is 1 min and by B is 2 mins.
Hence A, B, C and D all four will cross the bridge within 17 mins.
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