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 three-hour time intervals are shown in the table. t (hr) r(t) (L/h) 0 8.6 3 8 6 7.5 9 7 12 6.6 15 6.2 Find lower and upper estimates for the total amount of liquid that leaked out. lower estimate = liters upper estimate = liters