T = 0 4 7 9 (minutes)
r(t) = 9 6 4 3
(gallons per minute)
Water is flowing into a tank at the rate r(t), where r(t) is measured in gallons per minute and t is measured in minutes. The tank contains 15 gallons of water at time time i = 0. Values of r(t) for selected values of t are given in the table above. Using a trapezoidal sum with the three intervals indicated by the table, what is the approximation of the number of gallons of water in the tank at time t = 97?
(A) 52.
(B) 57.
(C) 67.
(D) 77.
(E) 79.