Quantitative Aptitude  Time and work  Formulae & Concepts Tutorial
 If A can do a piece of work in n day , then A’s 1 day work = .
 If A’s 1 day’s work = , then A can finish the work in n day.
 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.
 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
 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



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


 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?




180 + 15x = 270

x = 6 days

A alone can finish the remaining work in 6 days


 If A, B and C, finish a work in x, y and z days respectively, then they will together complete the work in days
 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