Question

Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes, and 10 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P,Q and R respectively. What is the proportion of the solution R in the liquid in the tank after 3 minutes?

Answer 1

In three minutes discharge in tank=
3*(1/30+1/20+1/10)
= 3*(11/60)=11/20;
In three minutes, liquid discharged by r= 3*(1/10)=3/10;
proportion of solution r = (3/10)/(11/20)= (3/10)*(20/11)=6/11;
Answer=6/11