Question 1139743: X can do a job in 16 days Y can do the same job in 20 days if X,Y and Z can do the job in 7.5 days . Alone Z can do the same job in ...? Answer by ikleyn(52781) (Show Source):
Rate of work for X is of the job per day.
Rate of work for Y is of the job per day.
The combined rate of work for X, Y and Z is = of the job per day.
Hence, the individual rate of work for Z is = (the common denominator is 240) = = = = .
It means that Z will complete the job in 48 days working alone. ANSWER
