Time and Work
- 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
- A does 2/5 of a work in 9 days. Then B joined him and they together completed the remaining work in 6 days. B alone can finish the whole work in
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Remaining work = 1 - 2 = 3 parts 5 5 ∵ (A + B) together do 3 th part of work in 6 days. 5
∴ Time taken by A and B in doing whole work= 6 × 5 = 10 days 3 A does 2 th part of work in 9 days. 5
∴ Time taken by A in doing whole work= 9 × 5 = 45 days 2 2 ∴ B’s 1 day’s work = 1 - 2 10 45 = 9 - 4 = 5 = 1 90 90 18
∴ Required time = 18 days .Correct Option: D
Remaining work = 1 - 2 = 3 parts 5 5 ∵ (A + B) together do 3 th part of work in 6 days. 5
∴ Time taken by A and B in doing whole work= 6 × 5 = 10 days 3 A does 2 th part of work in 9 days. 5
∴ Time taken by A in doing whole work= 9 × 5 = 45 days 2 2 ∴ B’s 1 day’s work = 1 - 2 10 45 = 9 - 4 = 5 = 1 90 90 18
∴ Required time = 18 days .
- John does 1/2 piece of work in 3 hours, Joe does 1/4 of the remaining work in 1 hour and George finishes remaining work in 5 hours. How long would it have taken the three working together to do the work ?
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According to the question
John does 1 work in 3 hours. 2
∴ Time taken by John in doing whole work = 6 hoursJoe does 1 work in 1 hour. 8
∴ Time taken by Joe in doing whole work = 8 hoursRemaining work = 1 - 1 2 8 = 4 - 1 = 3 parts 8 8
∴ Time taken by George= 8 × 5 = 40 hours 3 3
Work done by all three in 1 hour= 1 + 1 + 3 6 8 40 = 20 + 15 + 9 = 44 120 120 = 11 30 ∴ Required time = 30 = 2 8 hours 11 11 Correct Option: D
According to the question
John does 1 work in 3 hours. 2
∴ Time taken by John in doing whole work = 6 hoursJoe does 1 work in 1 hour. 8
∴ Time taken by Joe in doing whole work = 8 hoursRemaining work = 1 - 1 2 8 = 4 - 1 = 3 parts 8 8
∴ Time taken by George= 8 × 5 = 40 hours 3 3
Work done by all three in 1 hour= 1 + 1 + 3 6 8 40 = 20 + 15 + 9 = 44 120 120 = 11 30 ∴ Required time = 30 = 2 8 hours 11 11
