Aptitude - Chain Rule - Discussion

Discussion :: Chain Rule - General Questions (Q.No.8)

8. 

In a dairy farm, 40 cows eat 40 bags of husk in 40 days. In how many days one cow will eat one bag of husk?

[A]. 1
[B].
1
40
[C]. 40
[D]. 80

Answer: Option C

Explanation:

Let the required number of days be x.

Less cows, More days (Indirect Proportion)

Less bags, Less days (Direct Proportion)

Cows 1 : 40 :: 40 : x
Bags 40 : 1

1 x 40 x x = 40 x 1 x 40

x = 40.


Subhesh said: (Jul 30, 2010)  
Please explain another method to solve this prob if possible.

Mehar said: (Feb 2, 2011)  
Simple thing is one 40cows eat 40bags in 40days.
So, that mean 1cow eating 1bag 40days..

I want to solve this problem from reverse...lets think if 1cow eat 1 bag in 1day..for 40days 40cows*40bags=1600.

Now you got it?

Yadav said: (Mar 24, 2011)  
If 1 cow 1 bag in 1 day.
Then 40 cows 40 bags in 1day.
And 40 cows (40*40) bags in 40 days.

Navin said: (Apr 25, 2011)  
If there is any other method, please explain, other than ratio and proportion.

Eedha Koushik said: (Jul 10, 2011)  
I can't understand please explain another method.

Mini said: (Jul 18, 2011)  
40 cows eat 40 bags in= 40 days
1 cow eat 40 bags in =40*40=1600 days
1 cow eat 1 bag in=1600/40=40 days

Naresh said: (Aug 6, 2011)  
Please explain this problem by other method.

Moni said: (Aug 21, 2011)  
Any one explain about direct and indirect methods for three ratio.

Amal said: (Sep 14, 2011)  
This is damn confusing.

Vishal said: (Sep 16, 2011)  
40 cows 40 bags in 40 days. !

So 1 cow 1 bag each. But this is for 40 days since there are 40 cows and 40 bags.

Abhi said: (Nov 3, 2011)  
40 cows eat 40 bags in 1 day
Therefore work done by 40 cows = 40/40 = 1
work done by 1 cow = 1/40
Therefore 1 cow can do 1/40 of whole work
Hence 1/40 + 1/40 + 1/40.....40 times = 1 that is the whole work
Therefore 1 cow will take 40 days to eat 1 bag.

Ashis said: (Feb 15, 2012)  
@mini. Yaar you are explaining superly. Thanks a lot.

Deepak Varshney said: (Mar 26, 2012)  
40 cows eat 40 bags in 40 days
40 cows eat 40/40 bags in 1 days (i.e.40 cows eat 1 bags in 1 days)
therefore,
1 cow eat 1/40 bags in 1day
and
1 cow eat 1 bags in 40 day

Holy cowwa cowwa!!!

Ridhi said: (May 14, 2012)  
40 cows eat 40 bags in 40 days
40 cows eat 1 bag in 1 day
1 cow eat1/40 bags in 1day

Rupinderjit said: (May 30, 2012)  
40C-40D----40B
1C-1D----(40B/(40C*40D))
i.e. 1C-1D----1/40B

Now since 1 cow in 1 day consume 1/40 bags,that means

1/40B consumed in- 1Dday by cow is- 1
So 1B in 1D is 1/(1/40)==40 days

Shrey said: (Jul 31, 2012)  
Very simple:
40 cows eat 40 bags in 40 days!
Now in 1 day they eat 1 bag. i.e.40 cows eat 1 bag in 1 day.
Hence 1 cow will eat 1 bag in 40 days!!!!!

Saranya said: (Aug 9, 2012)  
Its a basic formula,

No.of cows*No.of days/No.of bags

40*40/40 = x*1/1

answer = 40.

Jyoti said: (Oct 2, 2013)  
Total work of 40 cows for 40 days = 40*40*40.

Work for 1 cow for 40 days = 40*40.

Work for 1 cow for 1 day = 40.

Chandan Kumar said: (Nov 10, 2013)  
Can anyone explain the chain rule in very simple way. How will I write the equation?

Smitha said: (Dec 28, 2013)  
40cows:40bags:40days = 1cow:1bag:xdays.

=>40:40:40=1:1:x.
=>40/40:40=1/1:x.
=>1:40=1:x.
=>x=40.

Nav said: (May 13, 2014)  
How convert direct and indirect proportion to ratio?

Himanshu Meena said: (Jul 5, 2014)  
40 cows 40 bags 40 days.

Considering cows and days.
40 cows 40 day.
=> 1 cow 1600 day(indirect proportion).

Above result is for 40 days.

So for 1 day ans = (1600)/40.
= 40 days.

Srinath said: (Jul 30, 2015)  
Explain easily method I can't understand this method.

Monty said: (Oct 1, 2015)  
Can anyone explain the direct and indirect method of 3 ration?

Lucky said: (Jan 20, 2016)  
40 cows/1 cow = 40 days/1 day (direct proportionate).

Let 40 cows/1 cow = c.

40 days/1 day = d.

c/40 bags = d/x bags.

Putting value of c = 40 & d = 40, we get x = 40;

Question will get rather tough when values differ (say 40 cows, 30 bags, 20 days and we have to find 1 cow to eat 1 bag in how many days.

Solution will be:

c = 40, d = 20 putting in direct relation.

= 40/30 = 20/x.

=> x = 15.

Direct hit method will not be applicable in such type of calculation based method.

Usman Ali Ar said: (Apr 7, 2016)  
Please give the answer without using ratio and proportion method.

Aku said: (Jul 15, 2016)  
@Navin.

I think this is the most simple and procedural method. Just think and got down on increasing one parameter how it affects the other parameter as simple as that,

But yet another initiative way to this problem:

40 cows eat 40 bags in days = 40.

So,1 cow will eat 40 bags in days = 40 * 40 (how? One cow will obviously take more time to eat as compared to 40 of them!).

1 cow will eat just 1 bag in days= (40 *40) /40 (how? 1 bag will require less time to be finished!).

= 40.

Kumar said: (Sep 24, 2016)  
40 cows eat 40 bags in 40 days, i.e 40 cows eat 1 bag in 1day.

In that 1 bag, each cow eats 1/40th in 1 day.

So, how many 1/40th make 1 bag.

1/40 * x = 1,

x = 40.

Mini said: (Jul 25, 2017)  
What if the cow eats more than its share of husk?

Magnesh said: (Aug 31, 2017)  
No equations nothing required, simple understanding
For better connection with the question, lets take boys and rice bags instead of cows and husk bags.

40 boys eat 40 bags of rice in 40 days

the gang of 40 boys eat 1 bag in 1 day
" " 40 boys eat 2 bags in 2 days
" " " " " 3 bags in 3 days

Similarly, group of 40 boys eats 40 bags in 40 days.

Think if 39 people are not there 1 boy can't eat 1 bag in 1 day it takes 40days for him to complete,

As good as saying 1 boy will take 40 days to eat 1 bag.

Sowmiya said: (Sep 2, 2017)  
Thanks for the explanation @Saranya.

Ruba said: (Jul 21, 2018)  
How to find direct & indirect proportion? Please tell me.

Ayushman Gautam said: (Nov 14, 2018)  
How it is possible for that 40 cows to take time 40 days, 1 cow is also 40 days?

So, according to me, it is option B.

Anomie said: (Apr 28, 2019)  
EASIEST METHOD:

First, we fix the data 40 days:
40 cows ----> 40 bags
1 cow -----> ? bags
? = 40 ÷ 40
=1 bag.

40 days ----> 1 bag
1 day -----> ? bag
? = 1 ÷ 40.
= 1/40 bag.

1 day ------> 1/40 bag.
? day -------> 1 bag.
? = 1 ÷ 1/40.
= 40 days.

Ashwani said: (Feb 8, 2020)  
M1D1 / W1 = M2D2 / W2.

(40cow x 40 days )/ 40 bag = (1Cow x D days)/ 1 bag.

(40 x 40)/40 =( 1 x D)/1.

40 = D.

Aadarsh said: (Jul 11, 2020)  
Nice Explanation. Thanks @Ashwini.

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