4. The Cannibals
Three cannibals and three anthropologists have to cross a river.
The boat they have is only big enough for two people. The cannibals will do as requested, even if they are on the other side of the river, with one exception. If at any point in time there are more cannibals on one side of the river than anthropologists, the cannibals will eat them.
What plan can the anthropologists use for crossing the river so they don't get eaten?
Note: One anthropologist can not control two cannibals on land, nor can one anthropologist on land control two cannibals on the boat if they are all on the same side of the river. This means an anthropologist will not survive being rowed across the river by a cannibal if there is one cannibal on the other side.
Added 1 January 2007
Solution:
First, two cannibals go across to the other side of the river, then the rower gets called back. Next, the rowing cannibal takes the second across and then gets called back, so now there are two cannibals on the far side.
Two anthropologists go over, then one anthropologist accompanies one cannibal back, so now there is one anthropologist and one cannibal on the far side.
The last two anthropologists go over to the far side, so now all the anthropologists are across the other side, along with the boat and one cannibal.
In two trips, the cannibal on the far side takes the boat and ferries the other two cannibals across the river.
Comments (18)
Can the solution for the 4 camels puzzle be applied to any number of camels on each side?
What type of man is that?
The puzzle states that two camels can pass through a narrow ledge, but it doesn't clarify how this is possible given the limited space.
I do not understand how the answer is 4.
This is a solution to an adaptation of 4 on the easy logic problems, the question about the cannibals and the anthropologists. If three anthropologists are on one side of a river (side x), and three cannibals are on the other side of the river(side y): 1. One cannibal (c) comes over by itself 2. Two anthropologists (a) go over Now we have one a and one c on side x of the river, and two a's and two c's on side y 3. Next, one a and one c go from side y to side x Now two a's and two c's or on side x, while one a and one c are on side y 4. The two a's on side x go to side y, leaving two c's on side x, while three a's and one c are on side y 5. the last c goes over to side x. Now there are three cannibals and three anthropologists on opposite sides of the river, and no anthropologist has been left with a majority of cannibals at any time.
This is a solution to an adaptation of the cannibals and anthropologists puzzle. If three anthropologists are on one side of a river and three cannibals are on the other side, one cannibal comes over by itself, followed by two anthropologists.
This is a solution to the Cannibals and Anthropologists puzzle. The steps provided do not ensure that the anthropologists are never outnumbered by the cannibals.
The hint for Logic Problem #4 is ridiculous. Robots don't get bored or lonely, they're machines.
The wording of puzzle number 4 should be rewritten for clarity.
Riddle 4's question and answer are unclear, making it difficult to understand before attempting to solve.
The scenario in question 8 could be improved. The man likely would have died due to dehydration from the high salt content of the Dead Sea, which could occur in thirty minutes. Adjusting the time to fifteen minutes might make the scenario more realistic.
There is a spelling mistake in the fourth problem of the lateral thinking preconception category. 'Storey' is incorrectly used as 'story'. Please correct it.
In puzzle #4, the wire would be too long, thus the resistance too high for the battery to light the bulb.
The baby can fall from a parachute with a static skate tied to its feet.
I think the solution to the cannibal puzzle allows for three one-way trips with one cannibal and one anthropologist each time, ensuring that there are never more cannibals than anthropologists.
I believe the cannibal puzzle can be solved by taking three one-way trips with one cannibal and one anthropologist at a time. At no point will there be more cannibals than anthropologists.
I believe I have a simpler method for solving question number 4 in the very difficult puzzles.
I found the Cannibals puzzle easier than expected and enjoyed it.
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