Selected MCQ

Current Question
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 1
Three pipes fill a tank in 6 houRs. After 2 hours, one is closed. Remaining time is ____.
  • A. 10
  • B. 12
  • C. 14
  • D. 16
Correct Answer: C
Explanation:
Work-rate adjustment.
Related Question 2
A tank is filled in 5 hours by three pipes, A, B, and C. If C is twice as fast as B, find the total time.
  • A. 20 hrs
  • B. 25 hrs
  • C. 35 hrs
  • D. Cannot be determined
Correct Answer: C
Explanation:
Solve rate equations.
Related Question 3
Three pipes of equal capacity fill a tank in 8 houRs. Two pipes will take ____.
  • A. 17 hours
  • B. 12 hours
  • C. 16 hours
  • D. 24 hours
Correct Answer: B
Explanation:
Work is inversely proportional.
Related Question 4
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 5
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.