Quantitative Aptitude - Time and work - Formulae & Concepts Tutorial

1. If A can do a piece of work in n day , then A’s 1 day work = .
2. If A’s 1 day’s work =  , then A can finish the work in n day.
3. If A can do a piece of work in x days and B can do the same work in y days, then both of working together will do the same in  days.
4. If A is thrice as good as workman as B , then ratio of work done by A and B = 3 : 1

Ratio of time taken by  A and B to finish a work = 1 : 3

5. Work Done = Men * Day

Example

Suppose 6 men and 8 boys can do  a work in 10 day. Similar work can be covered by 10 men and 6 boys in 8 days. What is the ratio of efficiency of the men and the boy

5. • • Let M is men and  B is boys

     • 10( 6 M + 8 B) = 8( 10 M + 6 B)

     • 60 M + 80 B = 80 M + 48 B

     • 32 B = 20 M

     • M : B = 8 : 5

6. When A, B, C finish a work in x, y, z days repectively one after another then finish work equal to 1.

i.e  

Example

A can finish a work in 18 days and B can do the same work in 15 day. B work for 10 days and left the job. In how many days, A alone can finish the remaining work?

6. • • 

     • 180 + 15x = 270

     • x = 6 days

     • A alone can finish the remaining work in 6 days

7. If A, B and C, finish a work in x, y and z days respectively, then they will together complete the work in   days
8. If A is x% more efficient than B. And A alone can complete a work in y day. Then

Time taken by B is

Time take by both A and B is