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 7 4 6.5 8 6.1 12 5.6 16 5.3 20 4.9 Find lower and upper estimates for the total amount of liquid that leaked out. lower estimate liters upper estimate liters