There are 17 perfectly rational lions and 1 lamb on a magical island. Lions only eat lambs; they will not eat each other. The magical thing about this island is that if a lion eats the lamb, it becomes the lamb by magical transformation. The lions are very intelligent and live by two rules: 1. Don’t get eaten. 2. Eat a lamb only if it doesn't result in a violation of rule number 1.
A biologist observes these 17 lions and 1 lamb for a little while and then leaves for several years. When the biologist returns, how many lions and how many lambs will remain?
You can find the answer here.
3 comment(s):
That was quite interesting because it showed a heuristic you could have used to solve it if you were smart enough (and it was a novel question and surprising answer).
FIRST; playing along with the premise yields the following:
i don't understand the rationale of the "answer" provided. given that if there is another lion present, the lion who eats the lamb will himself be eaten (as a lamb). then it doesn't matter whether there is an even or odd number of lions on the island to start.
if there's anything more than one lion to start, no lion will eat the lamb.
so, 17 lions to start, each one knowing that he will be eaten as a lamb if he eats the lamb himself, and so none do.
SECOND: the real answer
in two years, the lamb will be a ewe or ram, and will fall outside the parameters, and therefore will be eaten. unable to have reproduced (owing to there being only one lamb), there will then be NO lambs (or sheep) on the island. And since we do not know how many male and females lions there were to begin with, we do not have enough information to determine their likelihood of reproduction.
I suggest the answer is one sheep.
My grounds for this are... Lions only eat lamb. If a lion eats a lamb, it becomes the lamb, and therefore food for the next lion. But, eating the lamb is proscribed if it results in the lion being eaten. Therefore no lion eats the lamb, they all starve, and the lamb, being a grass eater, lives happily into old age.
Scenario 2, All the lions agree to simultaneously share the eating of the lamb, thus all become lambs, and then a flock of happy sheep, with no predators.
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