Liquid leaked from a damaged tank at a rate of r(t) liters per hour. The rate decreased as time passed and values of the rate at four-hour time intervals are shown in the table. t (hr) | r(t) (L/h) 0 10.5 4 9.8 8 9.1 12 8.5 16 8 20 7.4 Find lower and upper estimates for the total amount of liquid that leaked out. lower estimate = liters upper estimate = liters