In the table, [tex]$x$[/tex] represents minutes, and [tex]$y$[/tex] represents the altitude of an airplane.

\begin{tabular}{|c|c|}
\hline \multicolumn{2}{|c|}{ Altitude of an Airplane } \\
\hline Minutes, [tex]$x$[/tex] & Altitude in feet, [tex]$y$[/tex] \\
\hline 15 & 22,500 \\
\hline 20 & 20,000 \\
\hline 25 & 17,500 \\
\hline 30 & 15,000 \\
\hline \hline
\end{tabular}

Which statement is correct about the slope of the linear function that the table represents?

A. The slope is positive because as the minutes decrease, the altitude increases.

B. The slope is positive because as the minutes increase, the altitude increases.

C. The slope is negative because as the minutes decrease, the altitude decreases.

D. The slope is negative because as the minutes increase, the altitude decreases.



Answer :

To determine the correct statement about the slope of the linear function based on the given data points, let's follow these detailed steps:

1. Identify the Data Points:
We are given the following data points for minutes ([tex]\(x\)[/tex]) and altitude ([tex]\(y\)[/tex]):
[tex]\[ \begin{array}{|c|c|} \hline \text{Minutes, } x & \text{Altitude in feet, } y \\ \hline 15 & 22,500 \\ \hline 20 & 20,000 \\ \hline 25 & 17,500 \\ \hline 30 & 15,000 \\ \hline \end{array} \][/tex]

2. Select Data Points to Calculate Slope:
We need two points to calculate the slope of the linear function. Let's choose the points [tex]\((15, 22,500)\)[/tex] and [tex]\((30, 15,000)\)[/tex].

3. Calculate the Slope:
The slope [tex]\(m\)[/tex] of a line through two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is given by the formula:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]
Plugging in the points [tex]\((15, 22,500)\)[/tex] and [tex]\((30, 15,000)\)[/tex]:
[tex]\[ m = \frac{15,000 - 22,500}{30 - 15} \][/tex]
[tex]\[ m = \frac{-7,500}{15} \][/tex]
[tex]\[ m = -500 \][/tex]

4. Interpret the Slope:
The slope is [tex]\(-500\)[/tex]. A negative slope indicates that as the minutes increase, the altitude decreases. Hence, the rate of change is negative.

5. Determine the Correct Statement:
Based on the interpretation of the negative slope:

- The slope is not positive.
- As the minutes ( [tex]\(x\)[/tex] ) increase, the altitude ([tex]\( y \)[/tex]) decreases.

Therefore, the correct statement is:
The slope is negative because as the minutes increase, the altitude decreases.