# Four couples have to cross a river by small boat. At a time only 4 person can travel...

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Four couples have to cross a river by small boat. At a time only 4 person can travel and it takes 15 min to cross river from one bank to another. Find minimum time to cross the river by them?

posted May 10, 2015

## 2 Solutions

one side of river ;;;;;;;;;;;;;;;;;;;;;;;;;;;;; other side of river ,,,,,,, total time

``````   8 persons ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;  0 persons   ,,,,,,,,,,,,,,,,,  t=0

4  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;   4   ,,,,,,,,,,,,,,,,,,  15 min
5  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;   3   ,,,,,,,,,,,,,,,,,,   30
1  ';;;;;;;;;;;;;;;;;;;;;;;;;;;;;;   7  ,,,,,,,,,,,,,,,,,,  45
2   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;    6  ,,,,,,,,,,,,,,,,,,,  60
0   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;     8  ,,,,,,,,,,,,,,,,,,  75 min
``````

Hence total time is 75 min

solution May 11, 2015

minimum time will be thirty minutes

solution May 11, 2015
There is only one boat so 30 mins can't be the answer.

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