Latest IBM Aptitude Question SOLUTION: in a grass field, If there are 40 cows, they could eat for 40 days. If there are 30 cows, they could eat for 60 days. Than if 20 cows, How much day they could eat?

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in a grass field, If there are 40 cows, they could eat for 40 days. If there are 30 cows, they could eat for 60 days. Than if 20 cows, How much day they could eat?

Asked In IBM aditi sharma (12 years ago)

Unsolved Read Solution (9)

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Read Solution (9) :

ashutosh singh  (12 years ago)

40 COWS TAKE 4O DAYS
AND 30 COWS TAKE 60 DAYS
ITS OBVIOUS THAT 10 COWS LESS 20 DAYS MORE
SO 20 COWS WILL TAKE 80 DAYS

Is this solution Helpfull? Yes (22) | No (9)  

Abhiroop Mukherjee  (10 years ago)

let the no of units of grass growing each day is k...
let the already units of grass available is c...
hence.... 40(cows) X 40(days)= 40k+c.... (1)
& 30X60=60k+c...(2)
solve for k & C... PUT IN THE EQN 20x=kx+c... x=120(ans)

Is this solution Helpfull? Yes (7) | No (1)  

harigopal  (12 years ago)

nDays = k1 * nCows + k2
thus,
40 = 40k1 + k2
60 = 30k1 + k2
Solving for k1, k2;
k1 = -2, k2 = 120
Therefore,
in case of 20 cows:
nDays = 20*-2 + 120 = 80 days

Is this solution Helpfull? Yes (4) | No (4)  

atchutha reddy ambala  (9 years ago)

let initial amount of grass = x units.
let each cow eats 1 unit of grass everyday.
so 40 cows eat 40 units of grass in 1 day
and, 1600 (=40 x 40) units in 40 days.

Since they have cleared the lawn, and grass increases at some rate, they must have eaten more than the initial amount of grass, i.e, x.

Rate of growth of grass = (total grass eaten - initial amount) / number of days
= (1600 - x) / 40 units per day.

30 cows take 60 days to clear lawn, so equation becomes
[x + {(1600 - x) /40} x 60] / 30 = 60

=> x = 1200 units.

Rate of growth of grass = (1600 - 1200) / 40 = 10 units per day.

Now, 20 cows eat 20 units per day and 10 units of grass grow everyday, so net consumption is 10 units.

So, 1200 units of grass eaten at the rate of 10 units per day will take 120 days to finish

Is this solution Helpfull? Yes (2) | No (2)  

Mounika Chowdary  (12 years ago)

its simple logic for 40 cows- 40 days
for 30 cows-60 days
then for 20 cows-80 days it is obvious

Is this solution Helpfull? Yes (1) | No (10)  

sagarika chintala  (9 years ago)

40 cows takes 40 days.
40-10 =30 cows takes 40+20=60 days.
30-10=20 cows takes 60+20=80days.

Is this solution Helpfull? Yes (1) | No (1)  

Mohit tripathi  (12 years ago)

as per 10 cows ratio of days increase by 2 per 10 days so if there are 20 cows days will increase by 8 times i.e 8*40=320 days...so ans 320 days..

Is this solution Helpfull? Yes | No (13)  

Sireesha Musanalli Bugude  (7 years ago)

40 COWS TAKE 4O DAYS
AND 30 COWS TAKE 60 DAYS
ITS OBVIOUS THAT 10 COWS LESS 20 DAYS MORE
SO 20 COWS WILL TAKE 80 DAYS This is d right answer guys

Is this solution Helpfull? Yes | No (2)  

Pritam Ghosh  (7 years ago)

40cows eat 40 days
30 cows eat 60 days
20 cows eat 80 days

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