Task: Question Answering
Input (English): Problem: 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 solution q in the liquid in the tank after 3 minutes ? 
Options: a ) 1 / 11 , b ) 2 / 11 , c ) 3 / 11 , d ) 4 / 11 , e ) 5 / 11
Output (English): c