sjbouscher
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Posts posted by sjbouscher
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ranjha...look again...the cow can eat it all by itself in 7.5 days. the grass won't grow back in time...and even it it could, the constant trampling by the animal would turn the grassfield into a dirt field...
consider my previous answers for the time it takes each animal to do it by itself:
cow= 7.5 days
duck= 52.5 days
goat= 37.5 days
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the cow can eat the grass 7x faster than the duck:
52.5 / 7.5 = 7
the cow can eat 5x faster than than the goat:
37.5 / 7.5 = 5
the duck's time and the goat's time is subtracted from the cow's time since they are helping the cow out:
cow's time - duck's time -goat's time
cow - 1/5 cow - 1/7 cow
7.5 - (1/5)7.5 - (1/7)7.5 = total time
7.5 - 1.5 - 1.1 = total time
4.9 days total
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c + g = 45
c + d = 60
d + g = 90
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therefore...
d = 90- g
c = 45 - g
so, if c + d = 60...
(45 -g) + (90 - g) = 60 solve for g
g = 37.5
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c + g = 45
c + 37.5 = 45
c = 7.5
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d + 37.5 = 90
d = 52.5
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c= 7.5 days
d=52.5
g= 37.5
the values for c,d, and g are as stated....if they cow, duck or goat were eating by themselves... i shall try to work on what time it would take if they gave a group effort...i have to think about it more...probably using percentages?
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Newton's puzzle
in Brain Teasers and Puzzles
Posted
Bignose and DH, please refer to my post on september 10th...the math confirming each animal's time to do it by themselves is all there. those numbers are indeed correct. please take time to read it over.