A person P takes 4 hrs time to complete a job and Q takes 6 hrs to complete the same job if they work together how much time will they require to complete the job?  Choose the correct choice from the following choices:
A) 1.2 hrs	B) 1.8 hrs	C) 2.4 hrs	D) 3.0 hrs	E) none of these

Rationale: explanation : p ’ s 1 hr work = 1 / 4 q ’ s 1 hr work = 1 / 6 ( p + q ) ’ s 1 hr work = 1 / 4 + 1 / 6 = 5 / 12 = > time = 12 / 5 = 2.4 hrs answer : option c
Answer: C