A is twice as fast as B. If B can complete a work in 12 days, in how many days can A and B together complete the work? MCQ with Answer and Explanation

A is twice as fast as B. If B can complete a work in 12 days, in how many days can A and B together complete the work?
A. 3 days
B. 4 days
C. 8 days
D. 6 days
Answer: Option B
Solution (By JKSSB Mock Tests)
B takes 12 days, so A takes 6 days. Total work = 12 units. Efficiency of A = 2, B = 1. Combined efficiency = 3 units/day. Time taken together = 12 / 3 = 4 days.

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Practice More Time and Work Questions

Question #1
A can do a piece of work in 15 days and B in 20 days. They began the work together but A left after 4 days. In how many days will B complete the remaining work?
A. 10(1/3) days
B. 8 days
C. 10(2/3) days
D. 9(1/3) days

Correct Answer: Option C


Explanation:
Total work = LCM(15, 20) = 60 units. Efficiency of A = 4, B = 3. Combined efficiency = 7. In 4 days, work completed = 4 * 7 = 28 units. Remaining work = 60 - 28 = 32 units. Time taken by B to complete remaining work = 32 / 3 = 10(2/3) days.

This question belongs to: Maths Time and Work
Question #2
A can complete a work in 15 days and B in 15 days. If they work together, the work will be completed in:
A. 22.5
B. 12.5
C. 17.5
D. 7.5

Correct Answer: Option D


Explanation:
Combined rate = 1/15 + 1/15. Required time = 7.5 days.

This question belongs to: Maths Time and Work
Question #3
A can complete a work in 22 days and B can complete the same work in 32 days. If they work together, in how many days will the work be completed?
A. 13.04
B. 19.04
C. 15.04
D. 17.04

Correct Answer: Option A


Explanation:
Combined rate = 1/22 + 1/32. Time = 1 ÷ combined rate = 13.04 days.

This question belongs to: Maths Time and Work