1

# the cow

Sat 5 Nov, 2005 10:53 am
A cow can eat a third of the grass in a field in 3 days and the fourth
of grass in the same field in 2 days. How long will it take to eat the
entire grass.

• Topic Stats
• Top Replies
Type: Discussion • Score: 1 • Views: 939 • Replies: 14
No top replies

Chai

1
Sat 5 Nov, 2005 12:32 pm
10 days if you mean the cow could eat a 1/4 of the remaining grass in 2 days.
0 Replies

markr

1
Sat 5 Nov, 2005 12:37 pm
approximately 26 days
0 Replies

Merry Andrew

1
Sat 5 Nov, 2005 01:31 pm
Well...grass grows back, y'know.
0 Replies

markr

1
Sat 5 Nov, 2005 04:36 pm
I assumed the grass continues to grow until eaten.
0 Replies

whimsical

1
Sat 5 Nov, 2005 05:25 pm
"approximately 26 days"

0 Replies

Merry Andrew

1
Sat 5 Nov, 2005 05:26 pm
Not necessarily. Why is Whimsical grinning ear to ear at the bottom of his post? Cows browse, they don't tear up the grass by the roots. And they don't browse that close to the ground, either. After a herd of cows has passed over a pasture, there's plenty left for sheep. I think this is a trick riddle.
0 Replies

markr

1
Sat 5 Nov, 2005 05:32 pm
Merry Andrew wrote:
Not necessarily. Why is Whimsical grinning ear to ear at the bottom of his post? Cows browse, they don't tear up the grass by the roots. And they don't browse that close to the ground, either. After a herd of cows has passed over a pasture, there's plenty left for sheep. I think this is a trick riddle.

I may be wrong, but it was an assumption I made.
0 Replies

markr

1
Sat 5 Nov, 2005 05:40 pm
whimsical wrote:
"approximately 26 days"

I did this in Excel by approximating the growth and consumption of the grass in 1/100ths of a day. I tweaked the numbers to make the three-day consumption 4/3 of the two-day consumption. My final answer was a bit more than 26 days.
0 Replies

markr

1
Sat 5 Nov, 2005 06:43 pm
If the grass continues to grow after being eaten:
G = initial volume of grass (whole field)
g = volume of grass growth per day (whole field)
c = volume of consumed grass per day

2 days:
(G + 2g) / 4 = 2c
or
(i) G + 2g = 8c

3 days:
(G + 3g) / 3 = 3c
or
(ii) G + 3g = 9c (b)

subtract (i) from (ii) to get:
g = c
which means that the growth rate matches the consumption rate; so the field will never be completely consumed (unless I'm wrong).
0 Replies

Merry Andrew

1
Sat 5 Nov, 2005 08:27 pm
I have a feeling you're not wrong, markr.
0 Replies

whimsical

1
Sun 6 Nov, 2005 04:08 am
And so the answer is NEVER.
0 Replies

spidergal

1
Sun 6 Nov, 2005 06:01 am
ok, (x/4)+(x/3) = 5, so, 7x/12 = 5. Then, x = (12*5)/7 = 60/7 = 8 4/7 days
0 Replies

bobrath

1
Wed 4 Jan, 2006 12:41 am
12 days
0 Replies

bobrath

1
Wed 4 Jan, 2006 12:43 am
Exactly 12 days
0 Replies

### Related Topics

Alternative Einstein's riddle answer - Discussion by cedor
Urgent !!! Puzzle / Riddle...Plz helpp - Question by zuzusheryl
Bottle - Question by Megha
"The World's Hardest Riddle" - Discussion by maxlovesmarie
Hard Riddle - Question by retsgned
Riddle Time - Question by Teddy Isaiah
riddle me this (easy) - Question by gree012
Riddle - Question by georgio7
Trick Question I think! - Question by sophocles
Answer my riddle - Question by DanDMan52

1. Forums
2. » the cow