Pipe P can drain the liquid from a tank in 3/4 the time that it takes pipe Q to drain it and in 3/3 the time that it takes pipe R to do it. If all 3 pipes operating simultaneously but independently are used to drain liquid from the tank, then pipe Q drains what portion of the liquid from the tank?	Choose the correct answer
A) 9 / 29  B) 8 / 23  C) 3 / 8  D) 3 / 11  E) 3 / 4

Rationale: suppose q can drain in 1 hr . so , rq = 1 / 1 = 1 so , rp = 1 / [ ( 3 / 4 ) rq ] = 4 / 3 also , rp = rr / ( 3 / 3 ) = > 4 / 3 = rr / ( 3 / 3 ) = > rr = 4 / 3 let h is the time it takes to drain by running all 3 pipes simultaneously so combined rate = rc = 1 / h = 1 + 4 / 3 + 4 / 3 = 11 / 3 = 1 / ( 3 / 11 ) thus running simultaneously , pipe q will drain 3 / 11 of the liquid . thus answer = d .
Answer: D