1.If ‘m₁’ persons can do ‘w₁’ works in ‘d₁’ days and ‘m₂’ persons can do w₂ works in d₂ days, then we have a very general formula in the relationship of

m₁d₁w₂ = m₂ d₂ w₁

Again, if the time and efficiency of the persons in two groups is different then the relationship is

m₁d₁t₁e₁w₂ = m₂ d₂ t₂ e₂ w₁

2.If ‘A’ can do a job in ‘x’ days in ‘B’ can do it in ‘y’ days, then A&B working together,Will do the same work

4.If A&B together can do a piece of work in ‘x’ days in ‘A’ alone can do it in y days, then B alone can do the work in :

5.Pipe A can fill a tank in ‘x’ hours and pipe ‘B’ can empty it in ‘y’ hours. If both the pipes opened together, the tank will be filled in :

6.A Pipe can fill a cistern in ‘x’ hours but due to leakage in the bottom, it is filled ‘y’ hours.  Then time taken by the leak to empty the cistern in

Practice following examples

1)36 men can do a piece of work in 25 days. In how many days can 30 men do it?

1)20 days 2)25 days 3)30 days 4)35 days 5)none of these

Ans: 30 days

2)48 men can do a piece of work in 35 days. How many men will be required to finish it in 56 days?

1)28 2)40 3)15 4)30 5)none of these

Ans:30

3)32 men can do a piece of work in 15 days working 6 hours a day. In how many days will 40 men finish it if they work 8 hours a day?

1)12 days 2)18 days 3)16 days 4)9 days 5)none of these

Ans:9 days

4)A can do a job in 20 days and B in 30 days. In how many days can they finish it if thy work together?

1)25 days 2)12 days 3)15 days 4)22 days 5)none of these

Ans:12 days

5)10 men can do a job in 15 days. 15 boys can do it in 16 days. In how many days can 5 men and 8 boys do it?

1)30 days 2)25 days 3)15 days 4)35 days 5)none of these

Ans:15 days

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