Time and Work- QA Formulae

Work: Amount of job assigned or the amount of job actually done

Relations between work, time, and person:

• Work and person: Directly proportional, i.e., more work, more person required.
• Time and person: Inversely proportional, i.e., more people, less time required
• Work and time: Directly proportional, i.e., more work, more time required

Rules:

• If a person’s one day’s/hour’s work = 1/n, then they will complete the work in ‘n’ days/hours.

• If the first person is ‘n’ times more efficient than the second person, then the ratio of work done by the first person to the second person = n:1

• If the ratio of the number of men required to complete a work is m:n, then the ratio of time taken by them will be n:m. 

Formulas and quick tricks for time and work:

• If 1/n part of a work is done by A in one day, then A will take n days to complete the full work.
• If A can do a piece of work in X days and B can do the same work in Y days, then together they can do the same work in 
• If A, B, and C, alone can complete a work in X, Y, and Z days, respectively, then together they will complete the work in  days
• If A and B together can finish a piece of work in X days, B and C in Y days and C and A in Z days, then
  1- A, B, and C together can finish the job in 
  2- A alone will finish the job in 

        3- B alone will finish the job in 

         4- C alone will finish the job in 

If A can finish a work in X days and B is k times more efficient than A, then the time taken by both A and B working together to complete the work is 

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