There is a definite relationship between Time and Work. In this concept, there are only three factors:
There is a fundamental relationship between these three, discussed as follows:
Work done(W) = Number of days(Time taken)(T or D) times Number of men(M)
More number of men can do more work i.e. both are directly proportional
More number of men take less time to complete certain job i.e. both are inversely proportional
By summarizing, we get
Lets start solving some examples:
Example1: 10 men can cut 8trees in 16 days. In how many days can 6men cut 10trees?
Solution: This is a very simple example. You are given:
This means, "How much work one person can do in one day (expressed in percentage)"
For example: A person can do a job in 2days
This concept involves two steps to calculate efficiency:
Try the following example first, then re-read above points
Example2: If a person can complete his work in 5 days. What will be his efficiency?
Solution: Number of days a person take to complete his work = 5
Convert it into percentage:
Therefore, his efficiency is 20%.
Summarizing, If a person can do his job in n days, efficiency will be
For Example: Positive efficiency
As we all know, in competitive exams time management is very important. I suggest you to learn the fractions till 15.
|Number of days required to complete work||Work/Day||Efficiency (%)|
Example3: A can do a job in 10 days. B can do a job in 5 days. In how many days they can complete the job if they work together?
Solution: Consider the above table
A+ B efficiency
This means, In one day A and B together can do 30% of work.
Therefore,Number of days A and B together take to do 100% of work
Example4: A and B together can do a job in 4 days. If A can do job in 12 days if he works alone, then how many days B alone take to complete the job?
Solution: A+B take = 4 days
A takes = 12 days
This means, B can do 16.66% work in one day
Therefore, to complete the job he will take
Example5: A and B can do job in 8 days. B and C can do same job in 12 days. A, B and C together can do same job in 6 days. In how many days A and C together can complete the job?
Solution: You are given that:
we need to find A+C
Therefore, A and C takes
Hope you all understand this topic. I will soon update questions for your practice.