Atank contains 9000 l of pure water. brine that contains 20 g of salt per liter of water is pumped into the tank at a rate of 25 l/min. the concentration of salt after t minutes (in grams per liter) is c(t) = 20t/360+t as t → [infinity], what does the concentration approach?

20 g/L

Explanation:

To know what happens with the concentration, we must calcute the limit of the function where t → ∞. The limit is the value that the function approach when t intend to a value. So:

Dividing both for "t"

The limit of 1/t when t intend to infity is 0, which is demonstrated in the graph below, so:

The concentration will approach 20 g/L.