Target SBI PO: Time and Work (Top 50 Problems)

Mentor for Bank Exams
Performing any work or task involves efforts of Men over a period of time. Therefore the important variables in problems related to time and work  are , the  number of men (M) and the period of time to complete the work (W) and quantity of work (W) to be performed.
The time taken to perform a work not only depends on the number of men, but also depends on the efficiency of the men involved in the work.
Important Points to be remembered:
1. If a person can do a work in N days, in 1 day he can do 1/N of the work.
2. If M men can do a work in N days, in 1 day, 1 man can do 1/(M × N) of the work.
3. If M men can do a work in N days, then 1 man can do the same work in M × N days
4. If the ratio of time taken by A and B in doing a work = m : n, then the ratio of work done by A and B = 1/m : 1/n = n : m
5. The wages are always distributed based on the ratio of the efficiencies of people involved in the work.
6. If three men can a work in x, y and z days
-> the ratio of their efficiency = 1/x : 1/y : 1/z
-> the ratio in which the wages are distributed = 1/x : 1/y : 1/z
7. If A is n times more than B,i.e, A has n times capacity to do work that the capacity of B. A will take 1/n of the time taken by B to do the same amount of work.
8. The number of men involved to do a certain work to be changed in the ration M1:M2, the time required to do the same work will changed to its inverse ratio i.e, M2 :M1.
9. If A is X/Y times as a good a workman as B, the A will take Y/X of the time that B takes to perform the work.
10. If M1 men can do a work W1 in D1 days working H1 hours a day, and M2 men can do same kind of work W2 in D2 days working H2 hours a day, then
(M1 D1 H1)/W1 = (M2 D2 H2)/W2