Time and Work
Time and Work is a another important concepts in aptitude. Pipes and cistern is an application of time and work.
- Time and Work is directly proportional , where if work increases, time also increases.
- Work and person is directly proportional, where if work increases , persons also increases.
- Time and Person is inversely proportional , where if person increases ,time decreases.
Formulas :
- If `A` completes work in `n` days , then the work completed in one day is 1/n th part of work.
- If `A` completes 1/n th work in one day, then total work completed in `n` days.
- Let us assume `A` completes the work in `n` days and `B` completes the work in `m` days .Let us take work as only one unit, the amount of work done in one day by `A` is 1/n similarly for `B` is 1/m. So in how many days the work is completed if they work together then ,A + B = 1/n + 1/m.
Problems :
1. If `A` completes the work in 20 days and `B` completes the work same work in 30 days. In how many days both `A` and `B` completes the same work?
Ans :
Let us assume some units of work , so let us take LCM of both days that will be the total units of work.
Total units of work = 60 units.
`A` Completes the no of units work in One day = 60 / 20 = 3.
`B` Completes the no of units work in One day = 60 / 30 = 2.
No of days will take by both of persons is
= 60 / No of units completed in one day by `A` + No of units completed in one day by `B`
= 60 / 3+2
= 12
That is 12 days.
Comments
Post a Comment