shashi

• May 23rd, 2005

 

the ans is 60 days... as the ratio becomes 1:3 ie. 20(cows):60(days)

suresh

• May 31st, 2005

 

90 days

pani

• Jun 2nd, 2005

 

80 days

Raj

• Aug 23rd, 2005

 

days = infinity 
 
because  
40 * 40 * amount of grass taken by each cow = intial amount of grass + 40* grass grown per day 
 
similarly make eqn for 60days for 30 cows 
 
=> each day grass grows at the rate of grass intaken by 20 cow per day 
 
so grass taken 20 cows will be grown on next day  

simon

 Profile Answers by simon 

• Sep 22nd, 2005

 

if 10 cows r less days increse by 20

so if 20 days incrs by 40

so answer shud b 40+40

chinmay

• Nov 8th, 2005

 

the correct answer is 120 days

Sheetal Salunkhe

• Nov 21st, 2005

 

they could eat for 80 days

prashant

• Nov 26th, 2005

 

answer is 30 days

Karthikkeyan Vijayan

• Dec 6th, 2005

 

40 cows in 40 days.

30 cows = (40/30)*40 = 160/3 = 53 days.

imagine 'x' unit being taken by 1 cow in 1 day.

30 cows in 40 days qill take their share.

at the end of 40th day

40 (days)*10 (cows) share will be there remaining. (400* x) will be there.

means 1 cows share for 400 days.

30 cows = 400/30 = 13 more days.

so 40+13 = 53 days.

paswan

• Dec 25th, 2005

 

answer 80

LEE JUN SU

• Jan 3rd, 2006

 

Let amount of 1 cow?s eating for 1 day = x

40x * 40 = 30x * 60

x=2 , Total amount is 40*2*40 = 3200

therefore

 3200 = 20*2 * n days , n = 80 days

sonu

• Feb 12th, 2006

 

440 days

softwaregeek

• Apr 3rd, 2006

 

Zero. Because the farmer sent all the cows to slaugher house as he sold his farm to builder.

Rahul

• May 19th, 2006

 

This is correct. 30 days

priya vadhani

• Aug 25th, 2006

 

40 cows eat for 40 days

30 cows eat for 60 days

so, 10 less cows the days gained was 20 days

for 20 less cows the days gained (20*2)= 40 days

so, 40+40= 80 days

ans is 80 days

Jinho Hwang

• Oct 24th, 2006

 

a : consumption of 1 cow a day

b : growth of grass a day

T : total amount of grass at the begining

40*a*40 = T + 40*b ---- Equation 1)

30*a*60 = T + 60*b

so, b = 10*a

let's say we are looking for x which is the how-many-days to feed 20 cows.

20*a*x = T + x*b <- b = 10a

10*a*x = T ---- Equation 2)

Eq. 2) can be applied to Eq. 1)

Then, x = 120.

So, we can feed 20 cows in a grass for 120 days

hugo

• Feb 12th, 2007

 

40,4030,60linear co-ordinatesy=mx+cgradient m = 60-40 / 30-40 = -2using point 40,4040=-2(40)+c so C = 120y=-2x+cwhere x = 20-2*20 + 120 = 8020 cows eat for 80 days

RAVI

• Mar 16th, 2007

 

MY ANSWER IS 53
COWS         DAYS
 40                40
  30                X

40/30=X/40
X=160/3
THAT`S EQUAL TO
53

sathyacl

 Profile Answers by sathyacl 

• Jul 15th, 2008

 

The ans is 120

 cn = F+nr
c- no of cows, n- no of days, F- fixed length of grass,
r- rate at which it grows

40*40=F+40r
30*60=F+60r

r=10, F=1200 
for 20 cow n=120

mohdriz_ibm

 Profile Answers by mohdriz_ibm 

• Jul 21st, 2008

 

Ans : 80

sanjayjakhar

 Profile Answers by sanjayjakhar 

• Dec 26th, 2009

 

Suppose initial grass is d, and growth rate is r, so in 40 days 

d + r * 40 = 40 * 40 .......................... (1)

 

In 60 days

d + r * 60 = 30 * 60 ............................(2)

 

In w days

d +  rxw = 20 * w .............................(3)

From eqn { (3) - (2) } / { (3) - (1) }

After solving we will get w = 120 days

rohit

• Oct 1st, 2015

 

X+40*r=40*40*C.............1
X+60*r=60*30*C.............2
X+d*r=x*20*c.................3
Solve 1 2 then r=10c.........4
Solve equation 3 by using 4&1
(x=40*40c-40*r)&(r=10c)
Answer 120