Time and Work : Formula and Tricks with Problem (Question) and Solutions

Work is defined as the amount of job assigned or the amount of job actually done. The work to be completed is generally considered as one unit.

The following points are to be kept in mind while solving questions based on time and work.


1. It is assumed that a person does same amount of work each day.
2. Work and men are directly proportional.
3. Work and days are directly proportional
4. Men and days are inversely proportional

Important Points related to Time and Work as

 If a person takes x days to complete a work, then the work done in 1 day will be 1/x.

 If a person does 1/x th part of a work in one day, then person will finish the work in x days.

If A is x times more efficient than B to do a certain job, then A will take 1/x times more time than B to do that work.

Important Formulae

Formula 1

 Ex: A can do a work in 4 days while B can do that same work in 6 days. If they worked together, then that work would be completed in

Formula 2

If A,B and C can do a work in x, y and z days respectively, then they will complete the work in

Ex: A man, a woman and a boy can do a work in 3 days by working together. If a man and a boy can do that work in 6 days and 18 days respectively, then a woman can do it in

(a)12 days

(b)10 days

(c)9 days

(d)8 days

Formula 3

 If A and B can do a work x days and y days respectively. They Started working together and after t days A left the work. then time taken to Finish the complete work will be

 If B leave the work. then time taken to finish the complete work will be

Ex: A and B can do a work in 15 and 10 days respectively. They started work by working together but
after 2 days due to some reasons B left the work and A completed the remaining work. The complete work will be finished in

(a)12 days

(b)10 days

(c)11 days

(d)13 days

Formula 4

Ex: 15 men complete a work in 16 days. If 24 men are employed, then the time required to complete that work will be

(a) 7 days

(b) 8 days

(c) 10 days

(d) 12 days

Formula 5

 If A can do a work in x days and B can do y % fast than A, then B will complete the work in

Ex: x can do a work in 16 days. In how many days will the work be completed by y if the efficiency of y is 60 % more than that of x?

(a)12 days

(b)10 days

(c)11 days

(d)13 days

Formula 6

If A,B and C can do a piece of work in x, y and z days, respectively and they received k as wages by working together, then

If A and B can do a piece of work in x,  y days, respectively and they received k as wages by working together, then

Ex. A Completes a job in 2 days and B completes it in 3 days and C takes 4 days to complete it.
If they work together and get 3900 for the job, then how much amount does B get?

(a)1200

(b)1000

(c)1100

(d)1300

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