Pipes A, B, and C can fill an empty tank in 30 minutes, 20 minutes, and 10 minutes respectively. If all three pipes are opened simultaneously when the tank is empty, and each pipe delivers a different chemical solution—A delivers solution P, B delivers solution Q, and C delivers solution R—what fraction of the total liquid in the tank after 3 minutes is solution R?
Explanation
In 3 minutes, the combined volume filled by pipes A, B, and C is 3 × (1/30 + 1/20 + 1/10) = 11/20 of the tank. The volume contributed by pipe C alone in 3 minutes is 3/10. Therefore, the proportion of solution R in the tank after 3 minutes is (3/10) ÷ (11/20) = 6/11.