A can complete a piece of work in 12 days, while B can complete the same work in 15 days. If they work together, how many days will they take to complete the work? MCQ with Answer and Explanation

A can complete a piece of work in 12 days, while B can complete the same work in 15 days. If they work together, how many days will they take to complete the work?
A. 6 days
B. 5 days
C. 7 days
D. 6(2/3) days
Answer: Option D
Solution (By JKSSB Mock Tests)
Let the total work be the LCM of 12 and 15, which is 60 units. Efficiency of A = 60 / 12 = 5 units/day. Efficiency of B = 60 / 15 = 4 units/day. Combined efficiency of A and B = 5 + 4 = 9 units/day. Time taken together = 60 / 9 = 20 / 3 = 6(2/3) days.

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Practice More Time and Work Questions

Question #1
A and B work together. A alone can complete the work in 24 days and B alone in 26 days. What percentage of the total daily work is contributed by A?
A. 59.5
B. 57.0
C. 52.0
D. 54.5

Correct Answer: Option C


Explanation:
A share = (1/24) / (1/24+1/26) ×100 = 52.0%.

This question belongs to: Maths Time and Work
Question #2
4 men and 6 women can complete a work in 8 days, while 3 men and 7 women can complete it in 10 days. In how many days will 10 women complete the work?
A. 40 days
B. 35 days
C. 50 days
D. 45 days

Correct Answer: Option A


Explanation:
Total work = 8 * (4M + 6W) = 10 * (3M + 7W) => 32M + 48W = 30M + 70W => 2M = 22W => 1M = 11W. Total work = 8 * (4*11W + 6W) = 8 * 50W = 400W. Time taken by 10 women = 400W / 10W = 40 days.

This question belongs to: Maths Time and Work
Question #3
A and B work together. A alone can complete the work in 18 days and B alone in 28 days. What percentage of the total daily work is contributed by A?
A. 65.87
B. 63.37
C. 60.87
D. 68.37

Correct Answer: Option C


Explanation:
A share = (1/18) / (1/18+1/28) ×100 = 60.87%.

This question belongs to: Maths Time and Work