River flow: The graph in Figure 1.37 shows the mean flow F for the Arkansas River, in cubic feet of water per second, as a function of the time t, in months, since the start of the year. The flow is...

River flow: The graph in Figure 1.37 shows the mean flow F for the Arkansas River, in cubic feet of water per second, as a function of the time t, in months, since the start of the year. The flow is measured near the river’s headwaters in the Rocky Mountains.

a. Use functional notation to express the flow at the end of July, and then estimate that value.

b. When is the flow at its greatest?

 c. At what time is the flow increasing the fastest?