2 pipes P1 and P2 together can fill a tank in 6 hrs and P3 alone can fill the tank in 10 hrs if they work together what is the time taken to fill the tank?  Choose the correct choice from the following choices
A) 7/4 hrs  B) 9/4 hrs  C) 13/4 hrs  D) 15/4 hrs  E) 16/4 hrs
Explanation:   (P1 +P2) can fill 1/6 tank in 1 hr   P3 can fill 1/10 tank in 1 hr   (P1+P2+P3) can fill tank (1/6+1/10)= 4/15   =&gt;3 pipes can fill the tank in 15/4 hrs   Answer: Option 15/4 hrs
<result>D</result>
2 pipes P1 and P2 together can fill a tank in 6 hrs and P3 alone can fill the tank in 10 hrs if they work together what is the time taken to fill the tank?