A and B can do a piece of work in 45 and 40 days respectively. They began the work together, but A left after some days and B finished the remaining work in 23 days. After how many days did A leave? MCQ with Answer and Explanation

A and B can do a piece of work in 45 and 40 days respectively. They began the work together, but A left after some days and B finished the remaining work in 23 days. After how many days did A leave?
A. 6 days
B. 12 days
C. 8 days
D. 9 days
Answer: Option D
Solution (By JKSSB Mock Tests)
Total work = LCM(45, 40) = 360 units. Efficiency of A = 8, B = 9. B worked alone for 23 days: work done = 23 * 9 = 207 units. Remaining work = 360 - 207 = 153 units. This was done by A and B together. Combined efficiency = 8 + 9 = 17. Number of days they worked together = 153 / 17 = 9 days. Thus, A left after 9 days.

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Practice More Time and Work Questions

Question #1
A can complete a work in 17 days and B in 34 days. After working together for 5 days, what percentage of work remains?
A. 55.88
B. 60.88
C. 58.38
D. 63.38

Correct Answer: Option A


Explanation:
Remaining work = (1 - 5*(1/17+1/34))×100 = 55.88%.

This question belongs to: Maths Time and Work
Question #2
A can complete a work in 13 days and B can complete the same work in 23 days. If they work together, in how many days will the work be completed?
A. 14.31
B. 12.31
C. 8.31
D. 10.31

Correct Answer: Option C


Explanation:
Combined rate = 1/13 + 1/23. Time = 1 ÷ combined rate = 8.31 days.

This question belongs to: Maths Time and Work
Question #3
A can complete a work in 24 days and B can complete the same work in 19 days. If they work together, in how many days will the work be completed?
A. 10.6
B. 12.6
C. 14.6
D. 16.6

Correct Answer: Option A


Explanation:
Combined rate = 1/24 + 1/19. Time = 1 ÷ combined rate = 10.6 days.

This question belongs to: Maths Time and Work