A very large tank contains 1000L of pure water, and brine water with 50 g/L of salt is pumped into the tank at a rate of 3 L/min. Find a forumula for C(t), the concentration of salt (in g/L) in the tank's fluid after t minutes.

Every minute there are 3*50 = 150 grams of salt pumped in and 3 Litres of water, so after t minutes there are 150t grams in 3t + 1000 Litres. Hence C(t) = 150t/(3t + 1000) g/L

Every minute there are 3*50 = 150 grams of salt pumped in and 3 Litres of water, so after t minutes there are 150t grams in 3t + 1000 Litres. Hence C(t) = 150t/(3t + 1000) g/L