All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > General
Slow Cows (Posted on 2013-10-28) Difficulty: 3 of 5
Freddie the farmer has a paddock that he uses to graze his stock of cows. Each cow eats the same amount of grass each day, regardless of how many other cows are in the paddock and irrespective of the amount of grass left in the paddock. In an experiment, Freddie puts 6 cows into the paddock and he finds out it takes 3 days for them to eat all the grass. These 6 cows are then taken out of the paddock to allow the grass to grow back.

After the grass has been allowed to grow back to the original amount, Freddie then puts 3 cows into the paddock. This time he finds that it takes 7 days for the 3 cows to eat all the grass in the paddock. Freddie is puzzled that the cows took this long and consults a mathematician.

Freddie said "Geez mate, I dunno why me cows took that long to eat me paddock."
Marvin the mathematician replies "Well Freddie, tell me what assumptions you made."
Freddie replies "Well mate, maybe me cows got sick or somethin', cos I reckon that me 3 cows should have taken 6 days to eat me paddock, not 7 days! "
Marvin Replies, "I doubt that very much Freddie!"

After a while Marvin does some calculations and reveals that Freddie had overlooked an important assumption. What was the assumption Freddie had overlooked? Using Marvin's assumption, how long would a single cow take to eat the same paddock?

No Solution Yet Submitted by Danish Ahmed Khan    
Rating: 4.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Solution Comment 4 of 4 |

Let the rate at which grass grows is y and rate at which cow eats be x and initial grass in the paddock be c. Then

3*6*x=3*y+c and 7*3*x=7*y+c so y=3/4*x and c=63/4*x

Time for one cow to eat the grass if is A then

A*x=A*3/4*x+63/4*x or A=63 days


  Posted by Salil on 2013-10-29 06:43:11
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (0)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2021 by Animus Pactum Consulting. All rights reserved. Privacy Information