Time and Work
- A can do 1/3 rd of a work in 5 days and B can do 2/5 th of this work in 10 days. Both A and B, together can do the work in
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∵ A does 1/3 rd part of work in 5 days.
∴ A will do 1 work in 5 × 3 = 15 days.
∵ B does 2/5 th of work in 10 days∴ B will do 1 work in 10 × 5 = 25 days. 2
∴ (A + B)’s 1 day’s work= 1 + 1 15 25 = 5 + 3 = 8 75 75 ∴ Required time = 75 = 9 3 8 8 Correct Option: C
∵ A does 1/3 rd part of work in 5 days.
∴ A will do 1 work in 5 × 3 = 15 days.
∵ B does 2/5 th of work in 10 days∴ B will do 1 work in 10 × 5 = 25 days. 2
∴ (A + B)’s 1 day’s work= 1 + 1 15 25 = 5 + 3 = 8 75 75 ∴ Required time = 75 = 9 3 8 8
- A and B together can complete a work in 24 days. B alone does 1/3 rd part of this work in 12 days. How many days will A alone take to complete the remaining work?
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∵ B completes 1 work in 12 days. 3
∴ B will complete 1 work in 12 × 3 = 36 days.∴ B’s 1 day’s work = 1 36 (A + B)’s 1 day’s work = 1 24 ∴ A’s 1 day’s work = 1 - 1 24 36 = 3 - 2 = 1 72 72
∴ Time taken by A in doing 1 work = 72 daysRemaining work = 1 – 1 = 2 3 3
∴ Time taken by A in doing2 work = 2 × 72 = 48 days 3 3 Correct Option: C
∵ B completes 1 work in 12 days. 3
∴ B will complete 1 work in 12 × 3 = 36 days.∴ B’s 1 day’s work = 1 36 (A + B)’s 1 day’s work = 1 24 ∴ A’s 1 day’s work = 1 - 1 24 36 = 3 - 2 = 1 72 72
∴ Time taken by A in doing 1 work = 72 daysRemaining work = 1 – 1 = 2 3 3
∴ Time taken by A in doing2 work = 2 × 72 = 48 days 3 3
- A can do a certain job in 12 days. B is 60% more efficient than A. Then B can do the same piece of work in
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A can do a work in 12 days.
B is 60% more efficient than A.
∴ Time taken by B= 100 × 12 days 160 = 15 = 7 1 2 2 Correct Option: B
A can do a work in 12 days.
B is 60% more efficient than A.
∴ Time taken by B= 100 × 12 days 160 = 15 = 7 1 2 2
- Dhiru can dig 1/a of a field in 20 hours. What fraction of the same field can Kaku dig in 20 hours if the two of them can dig the field in 60 hours, working together at their respective rates ?
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∵ Dhiru digs 1 part of field in 20 hours. a
∴ Dhiru digs 1 part of field in 20a hours= 1 - 1 = a - 3 60 20a 60a
∴ Part of field dug by Kaku in 1 hour= 20(a - 3) = a - 3 60a 3a Correct Option: D
∵ Dhiru digs 1 part of field in 20 hours. a
∴ Dhiru digs 1 part of field in 20a hours= 1 - 1 = a - 3 60 20a 60a
∴ Part of field dug by Kaku in 1 hour= 20(a - 3) = a - 3 60a 3a
- A and B work together to complete the rest of a job in 7 days.However, 37/100 of the job was already done. Also, the work done by A in 5 days is equal to the work done by B in 4 days. How many days would be required by the fastest worker to complete the entire work?
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Remaining work
= 1 – 37 100 = 100 - 37 = 63 100 100
∴ Time taken by (A + B) in doing63 part of work = 7 days 100
∴ Time taken by them in doing whole work= 100 × 7 63 = 100 days 9
Respective ratio of time taken by
A and B in doing the work = 5 : 4∴ 1 + 1 = 9 4x 5x 100 ⇒ 5 + 4 = 9 20x 100
⇒ 20x = 100 ⇒ x = 5
∴ Required time
= 4 × 5 = 20 daysCorrect Option: A
Remaining work
= 1 – 37 100 = 100 - 37 = 63 100 100
∴ Time taken by (A + B) in doing63 part of work = 7 days 100
∴ Time taken by them in doing whole work= 100 × 7 63 = 100 days 9
Respective ratio of time taken by
A and B in doing the work = 5 : 4∴ 1 + 1 = 9 4x 5x 100 ⇒ 5 + 4 = 9 20x 100
⇒ 20x = 100 ⇒ x = 5
∴ Required time
= 4 × 5 = 20 days