Let’s make this one easy! Ankur with his friends went to river the bank of river Ganges, as the exams are over for fun and recreation. But while crossing to other side of the river, a storm came and he along with fourteen other people are trapped in a boat in the mid of the river. None of them know how to swim, and due to a hole in the base the boat is about to sink in 20 minutes. Their only chance to survival is the five-person raft stowed on their vessel.
But still, there is some ray of hope for these people. A round trip to the nearest side takes nine minutes on the raft. You have to help Ankur by telling that how many people will remain at raft so that he can go away by raft as soon as possible.
Solution: The correct answer is 2. You may give a cracking answer by giving the logic that after 2 rounds when (20 -18) i.e. only two minutes are left, the rest of five people can leave the boat. But dear, it’s a raft and you always need one person to move the raft, and that person has to return back with the raft to rescue other people. So the first time, 5 people went and one returned, again five went and one returned, and when only two minutes were left, five people went and no one returned leaving two people (20-(5-1) -(5-1)-5=2) back in the boat.
1ST Trip: 5-1, 11 minutes remaining
2nd Trip: 5-1, 2 minutes remaining
3rd Trip: 5, Time over
This Puzzle is contributed by Praveer Satyam. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.