The accompanying graph shows the total amount of gasoline $A$ in the gas tank of an automobile after it has been driven for $t$ days. (FIGURE CAN'T COPY)
a. Estimate the average rate of gasoline consumption over the time intervals $[0,3],[0,5],$ and [7,10]
b. Estimate the instantaneous rate of gasoline consumption at the times $t=1, t=4,$ and $t=8$
c. Estimate the maximum rate of gasoline consumption and the specific time at which it occurs.