P alone can complete a job in 4 days. The work done by Q alone in one day is equal to one-third of the work done by P alone in one day. In how many days can the work be completed if P and Q work together?  Choose the correct choice from the following choices.
A) 1.5  B) 2.0  C) 2.5  D) 3.0  E) 3.5

Rationale: p ' s rate is 1 / 4 q ' s rate is 1 / 12 the combined rate is 1 / 4 + 1 / 12 = 1 / 3 if they work together , the job will take 3 days . the answer is d .
Answer: D