Tap A can fill the water cooler in 20 minutes and Tap B can fill water cooler in 1 hour. Tap A is alone opened for 10 minutes. After 10 minutes, tap B is alone opened for 20 min. After this both taps are opened for 2 minutes, then tap B is closed. In what time remaining water cooler is completely filled by tap A?
Tap A can fill the water cooler in 20 minutes and Tap B can fill water cooler in 1 hour. Tap A is alone opened for 10 minutes. After 10 minutes, tap B is alone opened for 20 min. After this both taps are opened for 2 minutes, then tap B is closed. In what time remaining water cooler is completely filled by tap A? Correct Answer 40 seconds
Given,
Tap A's 1 min work = 1/20
Tap B's 1 min work = 1/60
Tap(A + B)’s 1 min work = 1/20 + 1/60 = 1/15
Tap A's 10 min work = 10/20 = 1/2
Tap B's 20 min work = 20/60 = 1/3
Tap (A + B)’s 2 min work = 2/15
Tank filled is = 1/2 + 1/3 + 2/15 = 29/30
Part of water cooler that is empty = 1 – 29/30 = 1/30
Tap A will fill 1/30th part of water cooler in =
= 1/30 × 20
= 2/3 minutes
= 2/3 × 60 seconds
= 40 seconds
মোঃ আরিফুল ইসলাম
Feb 20, 2025