A can do a piece of work in 12 days and B can do the same work in 18 days. They work together for 4 days and then A leaves. How many days will B take to complete the remaining work? MCQ with Answer and Explanation

A can do a piece of work in 12 days and B can do the same work in 18 days. They work together for 4 days and then A leaves. How many days will B take to complete the remaining work?
A. 8 days
B. 5 days
C. 6 days
D. 7 days
Answer: Option A
Solution (By JKSSB Mock Tests)
Total work = LCM(12, 18) = 36 units. Efficiency of A = 3, B = 2. Combined efficiency = 5. In 4 days, work completed = 4 * 5 = 20 units. Remaining work = 36 - 20 = 16 units. Time taken by B to complete the remaining work = 16 / 2 = 8 days.

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Practice More Time and Work Questions

Question #1
A can complete a work in 9 days and B in 13 days. If they work together, the work will be completed in:
A. 20.32
B. 5.32
C. 10.32
D. 15.32

Correct Answer: Option B


Explanation:
Combined rate = 1/9 + 1/13. Required time = 5.32 days.

This question belongs to: Maths Time and Work
Question #2
A can complete a work in 23 days and B can complete the same work in 28 days. If they work together, in how many days will the work be completed?
A. 16.63
B. 12.63
C. 18.63
D. 14.63

Correct Answer: Option B


Explanation:
Combined rate = 1/23 + 1/28. Time = 1 ÷ combined rate = 12.63 days.

This question belongs to: Maths Time and Work
Question #3
A, B and C can do a work in 6, 8 and 12 hours respectively. If they work together, how many hours will they take to complete the work?
A. 2(1/2) hours
B. 2(2/3) hours
C. 3 hours
D. 3(1/3) hours

Correct Answer: Option B


Explanation:
Total work = LCM(6, 8, 12) = 24 units. Efficiency of A = 4, B = 3, C = 2. Combined efficiency = 4 + 3 + 2 = 9. Time taken together = 24 / 9 = 8 / 3 = 2(2/3) hours.

This question belongs to: Maths Time and Work