25 multiple choice 4 points according to the graph, what is the average rate of change over the interval 20…

Explanation:

Step1: Recall average - rate - of - change formula

The average rate of change of a function $y = f(x)$ over the interval $[a,b]$ is $\frac{f(b)-f(a)}{b - a}$. Here, $a = 20$, $b = 40$, and $y$ is the temperature in degrees Fahrenheit and $x$ is the number of weeks after the spring equinox.

Step2: Estimate function values from the graph

From the graph, when $x = 20$, $y\approx60$ degrees Fahrenheit, and when $x = 40$, $y\approx10$ degrees Fahrenheit.

Step3: Calculate the average rate of change

Substitute into the formula: $\frac{f(40)-f(20)}{40 - 20}=\frac{10 - 60}{40 - 20}=\frac{- 50}{20}=-2.5\frac{\text{deg}}{\text{week}}$.

Answer:

$-2.5\frac{\text{deg}}{\text{week}}$