Selected MCQ

Current Question
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.
Related Question 1
Three pipes fill a tank. The first two together take 15 houRs. Find total time.
  • A. 6 hrs
  • B. 10 hrs
  • C. 15 hrs
  • D. 30 hrs
Correct Answer: C
Explanation:
Combined rate leads to 15 houRs.
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
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 4
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 5
Pipes P, Q, R fill the tank in 20, 15, 12 minutes. Together fill in ____.
  • A. 5 min
  • B. 10 min
  • C. 15 min
  • D. 20 min
Correct Answer: A
Explanation:
Combined rate.