Selected MCQ

Current Question
One tap fills the tank in 2 hours and another empties in 3 houRs. Time to fill tank is ____.
  • A. 5 hours
  • B. 6 hours
  • C. 7 hours
  • D. 8 hours
Correct Answer: B
Explanation:
Net rate = 1/2 − 1/3 = 1/6 → time = 6 hRs.
Related Question 1
One pipe fills a tank three times as fast as another. Together they fill in 36 minutes. The time taken by the slower pipe is ____.
  • A. 81 min
  • B. 108 min
  • C. 144 min
  • D. 192 min
Correct Answer: C
Explanation:
Let slow rate = x → total = 4x → gives 144 min.
Related Question 2
A water tank is two-fifths full. Pipe A fills it in 10 minutes, and pipe B empties it. What is the required time?
  • A. 6 min to empty
  • B. 6 min to fill
  • C. 9 min to empty
  • D. 9 min to fill
Correct Answer: A
Explanation:
Net rate depends on the stronger pipe; here, emptying dominates.
Related Question 3
A pipe fills a cistern in 8 hours and empties in 16 houRs. Net time to fill?
  • A. 8
  • B. 10
  • C. 16
  • D. 24
Correct Answer: C
Explanation:
Net rate = 1/16.
Related Question 4
A tap fills a tank in 6 houRs. After half filled, three more taps are opened. Total time is ____.
  • A. 3 hr 15 min
  • B. 3 hr 45 min
  • C. 4 hr
  • D. 4 hr 15 min
Correct Answer: B
Explanation:
Rate increases after half fill.
Related Question 5
A tap fills a tank in 32 min and empties in 16 min. Net fill time is ____.
  • A. 12 min
  • B. 14 min
  • C. 16 min
  • D. 20 min
Correct Answer: C
Explanation:
Net rate = difference.