Time and work formulas with examples for SSC and Bank Exams

Time and work formulas for Competitive Exams:

Formula with examples: 

Example.1. Worker A takes 8 hours to do a job. Worker B takes 10 hours to do the same job. How long should it take both A and B, working together but independently, to do the same job?

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Solution

Example.2. A and B together can complete a piece of work in 4 days. If A alone can complete the same work in 12 days, in how many days can B alone complete that work?

(A) 6

(B) 10 

(C) 12

(D) 14

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Solution

Hence, B alone can complete the work in 6 days. 

Example.3. A can do piece of work in 7 days of 9 hours each and B can do it in 6 days of 7 hours each. How long will they take to do it, working together  hours a day?

(A) 2

(B) 8 

(C) 5

(D) 3

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Solution

A can complete the work in (7×9) = 63 hours.

B can complete the work in (6×7) = 42 hours.

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Ex.4. A is twice as good a workman as B and together they finish a piece of work in 18 days. In how many days will A alone finish the work?

(A) 20

(B)  25 

(C) 27

(D) 30

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Solution

Hence, A alone can finish the work in 27 days.

Ex.5. A can do a certain job in 12 days. B is 60% more efficient than A. How many days does B alone take to do the same job?

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Solution

Ration of times taken by A and B = 160 : 100 = 8 : 5.

Suppose B alone takes x days to do the job.

Then, 8 : 5 : : 12 : x 

→ 8x = 5 × 12

 →  .
 

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