Question

Two pipes can fill a pool in 40 min and 48 min respectively and a waste pipe can empty 12 gallons per min. All the three pipes working together can fill the tank in 30 min. What is the capacity of the pool?
1. 960 gallons
2. 240 gallons
3. 480 gallons
4. 720 gallons

Answer 1

Correct Answer - Option 1 : 960 gallons

Given:

Two pipes can fill a pool = 40 min and 48 min

Waste pipe can empty = 12 gallon per min

All the three pipes working together can fill the tank = 30 min

Calculation:

Work done by the waste pipe in 1 min

⇒ 1/30 – (1/40 + 1/48)

⇒ 1/30 – (6 + 5)/240

⇒ 1/30 – 11/240

⇒ (8 – 11)/240

⇒ -3/240

⇒ -1/80      ––––[negative sign indicates emptying]

∴ volume of 1/80 part = 12 gallon

∴ volume of the whole pool

⇒ 80 × 12

⇒ 960 gallons

∴ Capacity of the tank = 960 gallons