CPM Homework Help : APCALC Problem 4-151

The annual cycle of daily high temperatures in Cabanaville is shown in the graph below from January 1st to December 31st. The $x$ -axis is marked in months and the $y$ -axis represents temperature in $^\circ\text{F}$ .

First quadrant, x axis with 12 tick marks, periodic curve starting on the y axis at y = 50, with 2 visible turning points at the first tick at y = 40, & at the seventh tick mark at y = 100.

Approximately when is Cabanaville at its hottest? The coldest? How can you tell?
Hint (a):
This is a temperature graph. Change in temperature is a rate. How is rate shown on a temperature graph? How about the 'fastest' rate?
When is the temperature changing the fastest? What is the name for this type point on
the graph?
Hint (b):
This is a temperature graph. During what month was temperature the highest?