Selected MCQ

Current Question
A pump fills a tank in 2 houRs. Due to leakage, it takes 2⅓ houRs. How long will the leak alone empty the tank?
  • A. 4⅓ hrs
  • B. 7 hrs
  • C. 8 hrs
  • D. 14 hrs
Correct Answer: D
Explanation:
Net rate difference gives leak empties in 14 houRs.
Related Question 1
If two pipes fill a tank in 6 hours, how long does one pipe take if the other fills in 10 hours?
  • A. 5 hours
  • B. 10 hours
  • C. 15 hours
  • D. 20 hours
Correct Answer: C
Explanation:
Using the rate formula gives 15 houRs.
Related Question 2
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 3
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 4
Pipes A, B, C fill tank in 12, 15, 20 houRs. If A alone works, time required is ____.
  • A. 6 hrs
  • B. 6⅔ hrs
  • C. 7 hrs
  • D. 7½ hrs
Correct Answer: C
Explanation:
Based on the given combination.
Related Question 5
Pipes A, B, C fill tank in 12, 15, 20 houRs. Find time together.
  • A. 6 hours
  • B. 6⅔ hours
  • C. 7 hours
  • D. 7½ hours
Correct Answer: C
Explanation:
Combined rate method.