Tuesday, July 14, 2009

One mower is good, two or three are even better

Imagine that you own a large castle in a countryside and preparing to host a big party there in a couple of days. For the party, you need to mow all the grass around your castle. You took Yellow Pages and called in three local gardeners. First of them told you that it would take him one whole week to mow all your grass. Second told you that it would take her two weeks. And a third one promised to do it in three weeks. In a hurry to get ready for a party in time, you hired all three of them to work in parallel. How long would it take for them?

Photo by Bobasonic, distributed under Creative Commons license.

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!


Kalonni said...

(1/7) + (1/14) + (1/21) = (1/X)
6 +3 +2 = (42/X)
11 = (42/X0
11X = 42
X = 3 and 9/11 days

Maria said...

That is right!
Someone else just answered on my Open Salon page, but you are first. I need to figure out how to direct all the answers toward this website. People read this feed in many places....

You are doing amazingly well, 9 solved puzzles!

Laura said...

That is the answer that I got assing that theowers would work seven days a week. If the assumption that a workweek is five days and not seven then the answer changes because they work at a faster pace making the time it would take decrease to two and 4/15 days.

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