1. Oil leaked from a tank at a rate of r(t) liters per hour. The rate decreased as time passed and values of the rate at two-hour time intervals are shown in the table below. Find lower and upper estimates for the total amount of oil that leaked out during the first 10 hours. t (hours) 0 2 6 8 10 r(t) (L/hr) 8.7 7.6 6.8 6.2 5.7 5.3