Aptitude - Chain Rule - Discussion

7 spiders in 7 days make 7 webs

Since 7 webs in 7 days.....1 web in 1 day..dis 1 web is made by 7 spiders.

Now,
Since 7 spiders have made 1web in a day
divide this 1 web into 7 parts 1 each for every spider..

So 1 spider will make 1/7 part of the web in a day.

Now,

1/7 th part completes in 1 day
so 1/7(1st day) + 1/7(2nd day) + 1/7(3rd day) + 1/7(4th day) + 1/7(5th day) + 1/7(6th day) + 1/7(7th day) = 7/7 = 1 complete web by a spider...

Thus it took 7 days which is the answer.

7 Spiders make 7 Webs in 7 Days. -> eq 1
7 Spiders make 1 Web in 1Day -> eq 2
1 Spider make 1 Web in X=? Days) -> eq3

Multiple Value of Number of Spiders with a number of days from eq 2 and eq3

7*1. = 1*X.
X. =. 7*1/1,
X. = 7 -----> Ans.

Less Spiders -> More Days (Indirect Proportion).
Less Webs -> fewer Days (Direct Proportion).

Take this example.

7 girls make 7 cakes in 7 days.
so 7 girls complete 1 cake in 1 day.
7 girls complete 2cakes in 2days.
7 girls complete 3 cakes in 3 days.
Similarly, 7 girls make 7 cakes in 7 days.

Simply can say effort of 7 girls is needed for 1 cake to complete in 1 day as good as saying effort of 1 girl is required for 7 days to make 1 cake.

To get 7 then I think it needs to be explained better that each spider is working on their own web.

Otherwise, it takes 1 team of 7 spiders 7 days to make 7 webs. If you have less on your team you will make fewer webs or it will take longer to make the same number of webs.

7 Spiders ... 7 Days.

=> 1 spider =7*7= 49 days--- Eq(1).

Remaining one is 7 Webs--- Eq(2).

But, question is about 1 web. So, when we Divide Eqn(1) by Eqn(2) we get 1 web.

=>1 spider =49 days/7 webs = 7 days/1web

=>1 spider 1 web = 7 days

When ever you found these kind of problems, come from the back.

Means if 7spiders 7weds in 7days so,

1 spider work ==(7*7)/7=7;

one person work==days*work done/ number of workers;

7spiders * 1spider * x days = 7webs * 1web * 7days.
Spiders on the Left * days = webs on the right * days.
=> 7 * 1 * x = 7 * 1 * 7.
7x = 49,
7x/7 = 49/7,
x = 7days.

hw that problem has been solved i don't understand the way it has been solve out...plz tell me the way it has been solved out

I didn't understood how the ratio will be considered. As follows
1*7*x=7*1*7

So please give the brief description.

Its simple formula:-

(no. of spider*no.of days)/no.of webs

So according this:

7*7/7 = 1*x/1.
Than x = 7.