A graphing calculator is recommended.

A 20-gallon barrel is filled completely with pure water. Salt water with a concentration of 0.3 lb/gal is then pumped into the barrel, and the resulting mixture overflows at the same rate. The amount of salt in the barrel at time t is given by Q(t) = 6(1 − e−0.02t) where t is measured in minutes and Q(t) is measured in pounds.

How much salt is in the barrel after 3 min? (Round your answer to two decimal places.)