# The cow and the butcher

Let’s have 12 stalls spaced equidistantly, and a cow traveling between them. In the 12th stall a butcher is waiting with a sharp knife. So the farthest stall a cow wants to reach is the 11th stall. In each stall is a trough which contains 4 liters of water. When the cow drinks water from the trough it has to drink all 4 liters. To travel from stall to stall one way the cow requires/″ burns″ 1 liter of water. The forward trip is from the first stall to the eleventh. After the cow has a 2nd drink, she goes back one stall before moving forward. This repeats on the 3rd and 4th drinks, and so on. When the cow reaches the 11th stall, all the water she drank during the trip has to have been burned. Now the cow has to return from the 11th stall back to the first. The same conditions apply for the return trip. The question is: For both trips, from how many stalls did the cow have a drink and how many liters of water did she drink in total?

HINT: One way to approach the unique solution starts with the following. Going forward the cow drinks from the 1st, 2nd, 3rd, and 9th stalls...

• I'm not sure what's the puzzle here. The question seems to have described the exact trip route, and we simply just need to add up the amount of water, which is basically the number of stalls visited times 4? Oct 23, 2021 at 7:53
• So the "butcher" who appears in the title does nothing but waiting in the last stall? Oct 24, 2021 at 7:47