Selected MCQ

Current Question
A can complete the work in 12 days and B in 18 days. In how many days will they complete the work together ____.
  • A. 6 days
  • B. 7.2 days
  • C. 8 days
  • D. 9 days
Correct Answer: B
Explanation:
Combined work = (1/12 + 1/18) = 5/36 → time = 36/5.
Related Question 1
P and Q complete work in 15 and 10 days. Together they complete in ____.
  • A. 6
  • B. 12
  • C. 22
  • D. 20
Correct Answer: A
Explanation:
Combined rate = 1/15 + 1/10 = 1/6 → time = 6 days.
Related Question 2
P completes work in 24 days, Q in 9 days, R in 12 days. Time taken together is ____.
  • A. 10
  • B. 9
  • C. 11
  • D. 12
Correct Answer: A
Explanation:
Sum of rates gives time = 10 days.
Related Question 3
P and Q complete work in 20 and 12 days. Time together is ____.
  • A. 5 days
  • B. 10 days
  • C. 15 days
  • D. 12 days
Correct Answer: B
Explanation:
The combined rate gives 10 days.
Related Question 4
If 9 workers can complete a job in 6 days, how many days will 3 workers take?
  • A. 12
  • B. 15
  • C. 18
  • D. 20
Correct Answer: C
Explanation:
Work = 54 ⇒ 54/3 = 18.
Related Question 5
If 8 workers can complete a job in 15 days, how many workers are needed to complete it in 10 days?
  • A. 10
  • B. 12
  • C. 14
  • D. 16
Correct Answer: B
Explanation:
Work = 8×15 = 120 ⇒ workers = 120/10 = 12.