A lion takes 5 hours to eat a sheep or 1 hour to eat 1/5 of a sheep.
A leopard takes 6 hours to eat a sheep or 1 hour to eat 1/6 of a sheep.
A cheetah takes 7 hours to eat a sheep or 1 hour to eat 1/7 or a sheep.
In one hour, the three animals eat 1/5 + 1/6 + 1/7 = 107/210 of a sheep, roughly half a sheep.
Therefore, the three animals take roughly two hours (1.962 hours to be exact) to eat a whole sheep.
Well done DraeKlae! That is the right answer 
it's a harmonic sum
Good question and good thiiking by draeklae..
This problem took me ages, because I had to go find a cheetah, a leopard and a sheep to find out. Unfortunately none of us was wearing a watch, but we all enjoyed the problem anyway. Except the sheep.
A lion takes 5 hours to eat 1 sheep.
A leopard takes 6 hours to eat 1 sheep.
A cheetah takes 7 hours to eat 1 sheep. Assuming that the lion, leopard and the cheetah were friends, how much time would it take to eat 1 sheep.