-ve Series

[manu.pant]

A chemical plant has four tanks (A, B, C and D), each containing 1000 litres of a
chemical. The chemical is being pumped from one tank to another as follows:
From A to B @ 20 litres/minute From C to A @ 90 litres/minute From A to D @ 10
litres/minute From C to D @ 50 litres/minute From B to C @ 100 litres/minute
From D to B @ 110 litres/minute Which tank gets emptied first and how long does it
take (in minutes) to get empty after pumping starts?


Ans: C, 20

[jaxis]

A chemical plant has four tanks (A, B, C and D), each containing 1000 litres of a
chemical. The chemical is being pumped from one tank to another as follows:
From A to B @ 20 litres/minute From C to A @ 90 litres/minute From A to D @ 10
litres/minute From C to D @ 50 litres/minute From B to C @ 100 litres/minute
From D to B @ 110 litres/minute Which tank gets emptied first and how long does it
take (in minutes) to get empty after pumping starts?


Ans: C, 20

Shouldnt it be D,20.

[manu.pant]

Correction: D, 20

[Anurag@Gurome]

From A to B @ 20 L/min
From C to A @ 90 L/min
From A to D @ 10 L/min
From C to D @ 50 L/min
From B to C @ 100 L/min
From D to B @ 110 L/min

Let us determine the final IN(+) or OUT(-) rate for each of the tank,

• For A : -20 (to B) + 90 (from C) - 10 (to D) = +60 L/min
  For B : +20 (From A) - 100 (to C) + 110 (from D) = +30 L/min
  For C : -90 (to A) - 50 (to D) + 100 (from B) = -40 L/min
  For D : +10 (from A) + 50 (from C) - 110 (to B) = -50 L/min

As D has the maximum outlet rate of 50L/min, it'll empty first.
It'll take (1000/50) = 20 min to empty.

[manu.pant]

how can we find the time taken thru -ve series??