Aptitude - Chain Rule - Discussion

3 pumps working 8 hours.
So total hours = 3 * 8 = 24 * 2 = 48 to fill.
So can empty 48/4 = 12 hours.
Then, the answer = 12.

Maths Master Really Explained It Well. I Need More Of Your Teaching.

Let pumps - 'p', no.of hrs/day - 'h', no.of days - 'd'.

For this type of problems, first know what we have to find? here we have to find hrs/day i.e. 'h'.

Now, find out the relation of 'h' with other parameters 'p' and 'd'.

If no.of pumps increases, no.of hrs/day decreases (inverse proportion).

p & (1/h). (1) **Assume &-proportionality symbol**.

If no.of days increases, no.of hrs/day decreases (inverse proportion).

d & (1/h). (2).

From (1) & (2).

pd & (1/h). (3).

=> pdh=constant.

=> p1*d1*h1=p2*d2*h2.

=> 3*2*8=4*1*x.

=> x=12.

3 pumps = 8 hrs/day.

1 pump = 8*3 = 24 hrs/day and 48 hrs in 2 days.

Considering 1 day work of 3 pumps we know that 24/3 = 8.

Now f we consider 1 day work of 4 pumps should not it be 24/4 = 6.

Please anyone, why? are we considering for two days when it is asked for 1 day work?

3 pumb work in 2 days = 16 hours for empty the tank
1 pump work in 2 days = 16*3 = 48 hours for empty the tank
so 4 pump ...........= (16*3)/4 = 12..

3 pumps -> 8h -> 2 days.

4 pumps -> ? -> 1 day.

3*8*2/4*1 = 12.

One pump requires 16 *3 = 48 hrs to empty the tank.

4 pump requires 48/4 = 12 hrs.

pumps*days*hours=pumps*days*hours.

4*1*x=3*8*2.

x=12.

That's simple

At First we find the Total_hour to finish the work, that is:

3*8*2 = 48.

So, 4*X*1 = 48.

X = 48/4 = 12.

Hey I have one simple way that is ma formula is n*D*H/w = N1*D1*H1/W1.

Where n = no.of men.
d = days.
h = hours.
w = work.

So my opinion is 3*8*2 = 4*1*x.

x = 12.