Transcript text: In this example we considered the function $W=f(T, v)$, where $W$ is the wind-chill index, $T$ is the actual temperature, and $v$ is the wind speed. A numerical representation is given in this table.
(a) What is the value of $f(-15,60)$ ? What is its meaning?
We get $f(-15,60)=$ $\square$ , which means that if the temperature is $-15^{\circ} \mathrm{C}$ and the wind speed is $60 \mathrm{~km} / \mathrm{h}$, then the air would feel equivalent to approximately $\square$ ${ }^{\circ} \mathrm{C}$ without wind.
(b) Describe in words the meaning of the question "For what value of $v$ is $f(-20, v)=-30$ ?"
The question is asking: when the temperature is $\square$ ${ }^{\circ} \mathrm{C}$, what wind speed gives a wind-chill index of $\square$ ${ }^{\circ} \mathrm{C}$ ?
Answer the question.
$v=$ $\square$ $\mathrm{km} / \mathrm{h}$
(c) Describe in words the meaning of the question "For what value of $T$ is $f(T, 20)=-43$ ?"
The question is asking: when the wind speed is $\square$ $\mathrm{km} / \mathrm{h}$, what temperature gives a wind-chill Index of $\square$ ${ }^{\circ} \mathrm{C}$ ?
Answer the question.
$T=$ $\square$ ${ }^{\circ} \mathrm{C}$
(d) What is the meaning of the function $W=f(-10, v)$ ? Describe the behavior of this function.
The function $W=f(-10, v)$ means that we fix $T$ at $\square$ and allow $v$ to vary, resulting in a function of one variable. In other words, the function gives wind-chill index values for different wind speeds when the temperature is $\qquad$ ${ }^{\circ} \mathrm{C}$. From the table (look at the row corresponding to $T=-10$ ), the function - Select $-\checkmark$ and appears to approach a constant value as $v$ increases.
(e) What is the meaning of the function $W=f(T, 80)$ ? Describe the behavior of this function.
The function $W=f(T, 80)$ means that we fix $v$ at $\square$ and allow $T$ to vary, again giving a function of one variable. In other words, the function gives wind-chill index values for different temperatures when the wind speed is $\square$ $\mathrm{km} / \mathrm{h}$. From the table (look at the column corresponding to $v=80$ ), the function -Select $-v$ almost linearly as $T$ Increases.