2023 · Q43
Suppose A, B and C are three taps fixed to the bottom of a tank with draining capacity 1 : 2 : 3. When all three of them are on, it takes 1 hour to drain out the full tank. If A and C are on but B is off, then how much time, in minutes, will it take to empty out a full tank of water?
general-mental-abilityquantitative-aptitude
- A75
- B90
- C105
- D120
Explanation
Take the tank's capacity as 6 units. All three taps together drain 1+2+3 = 6 units per hour, emptying the full tank in 1 hour. With taps A and C on and B off, the combined draining rate is 1+3 = 4 units per hour. Emptying the 6-unit tank then takes 6/4 = 1.5 hours, which is 90 minutes. Hence option B.