Question

A contractor has two teams of workers: team A and team B. Team A can complete a
job in 12 days and team B can do the same job in 36 days. Team A starts working on
the job and team B joins team A after four days. The team A withdraws after two more
days. For how many more days should team B work to complete the job?

Answer 1

Rate of team a = 1/12


Rate of team b = 1/36

Combined rate = 1/12 + 1/36 = 1/9

Fraction done in 4 days = 4x1/12 = 1/3


Remaining fraction = 1-1/3 = 2/3

Two days working together
Fraction done = 2x1/9 = 2/9


Remaining fraction = 2/3 – 2/9 = 4/9


Number of days it will take team b to complete the job = (4/9)/(1/36)
= 16 days