A and B can complete a work in 15 days and 10 days respectively. They started the work together but B left after 2 days. In how many days will A complete the remaining work? MCQ with Answer and Explanation

A and B can complete a work in 15 days and 10 days respectively. They started the work together but B left after 2 days. In how many days will A complete the remaining work?
A. 8 days
B. 11 days
C. 10 days
D. 9 days
Answer: Option C
Solution (By JKSSB Mock Tests)
Total work = LCM(15, 10) = 30 units. Efficiency of A = 2, B = 3. Combined efficiency = 5 units/day. In 2 days, work completed = 2 * 5 = 10 units. Remaining work = 30 - 10 = 20 units. Time taken by A to complete remaining work = 20 / 2 = 10 days.

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Practice More Time and Work Questions

Question #1
A can do a work in 9 days and B in 23 days. In how many days will they complete 75% of the work together?
A. 12.35
B. 9.85
C. 4.85
D. 7.35

Correct Answer: Option C


Explanation:
Combined time for full work multiplied by 0.75 = 4.85 days.

This question belongs to: Maths Time and Work
Question #2
A can complete a work in 19 days and B in 19 days. If both work together, in how many days will the work be completed?
A. 9.5
B. 17.0
C. 14.5
D. 12.0

Correct Answer: Option A


Explanation:
Combined rate = 1/19 + 1/19. Time = 9.5 days.

This question belongs to: Maths Time and Work
Question #3
A and B working separately can do a piece of work in 9 and 12 days respectively. If they work for a day alternately, A beginning, in how many days will the work be completed?
A. 10(1/4) days
B. 10(1/2) days
C. 11 days
D. 10 days

Correct Answer: Option A


Explanation:
Total work = LCM(9, 12) = 36 units. Efficiency of A = 4, B = 3. In 2 days (A + B), work done = 4 + 3 = 7 units. In 10 days (5 pairs of 2 days), work done = 7 * 5 = 35 units. Remaining work = 36 - 35 = 1 unit. On the 11th day, it is A's turn. Time taken by A to complete 1 unit = 1/4 day. Total time = 10 + 1/4 = 10(1/4) days.

This question belongs to: Maths Time and Work