A can complete a work in 21 days and B in 42 days. After working together for 5 days, what percentage of work remains? MCQ with Answer and Explanation

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A can complete a work in 21 days and B in 42 days. After working together for 5 days, what percentage of work remains?

A. 69.29

B. 71.79

C. 66.79

D. 64.29

Answer: Option D

Solution (By JKSSB Mock Tests)

Remaining work = (1 - 5*(1/21+1/42))×100 = 64.29%.

This question belongs to: Maths Time and Work

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Question #1

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A is twice as fast as B. If A and B together can complete a piece of work in 8 days, in how many days can A alone complete it?

A. 16 days

B. 10 days

C. 12 days

D. 24 days

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Correct Answer: Option C

Explanation:
Let efficiency of B = 1, then efficiency of A = 2. Combined efficiency = 3 units/day. Total work = 8 * 3 = 24 units. Time taken by A alone = 24 / 2 = 12 days.

This question belongs to: Maths Time and Work

Question #2

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A can complete a work in 24 days and B can complete the same work in 24 days. If they work together, in how many days will the work be completed?

A. 16.0

B. 14.0

C. 12.0

D. 18.0

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Correct Answer: Option C

Explanation:
Combined rate = 1/24 + 1/24. Time = 1 ÷ combined rate = 12.0 days.

This question belongs to: Maths Time and Work

Question #3

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18 men can complete a work in 16 days. If 22 men work at the same rate, in how many days will the work be completed?

A. 15.09

B. 17.09

C. 19.09

D. 13.09

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Correct Answer: Option D

Explanation:
Total work = 18 × 16 = 288 man-days. Required days = 288/22 = 13.09 days.

This question belongs to: Maths Time and Work

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