Selected MCQ

Current Question
Machine P prints 1 lakh books in 8 hrs, Q in 10 hrs, R in 12 hRs. All start together. When will 1 lakh be printed?
  • A. 3 pm
  • B. 2 pm
  • C. 1 pm
  • D. 11 am
Correct Answer: C
Explanation:
Combined rate gives 4 hrs → 1 pm.
Related Question 1
A and B can do the work in 15 and 10 days. If they start together and A leaves after some days, total time ____.
  • A. 8 days
  • B. 10 days
  • C. 12 days
  • D. 15 days
Correct Answer: C
Explanation:
Solve with work fractions.
Related Question 2
10 books placed randomly. Probability a pair stays together ____.
  • A. 1/10
  • B. 9/10
  • C. 1/5
  • D. 3/10
Correct Answer: C
Explanation:
Treat the pair as one unit.
Related Question 3
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.
Related Question 4
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 5
Three pipes, A, B, and C, fill the tank in 30, 20, and 15 minutes, respectively. Together they fill in ____.
  • A. 5/11
  • B. 6/11
  • C. 7/11
  • D. 8/11
Correct Answer: B
Explanation:
Combined rate calculation.