The cost to rent a movie at a video store can be modeled by a linear function. The table shows the total costs of renting a movie for different lengths of time. Based on the table, which statement is true?

\begin{tabular}{|c|c|}
\hline
Nights rented, [tex]$x$[/tex] & Total cost (dollars), [tex]$y$[/tex] \\
\hline
1 & 1.50 \\
\hline
2 & 2.75 \\
\hline
3 & 4.00 \\
\hline
4 & 5.25 \\
\hline
5 & 6.50 \\
\hline
\end{tabular}

A. The slope is 1.5. It represents the initial cost.

B. The slope is 1.5. It represents the rate per night.

C. The slope is 1.25. It represents the initial cost.

D. The slope is 1.25. It represents the rate per night.



Answer :

To determine the correct statement, let's analyze the table and understand the linear function that models the cost to rent a movie.

[tex]\[ \begin{array}{|c|c|} \hline \text{Nights rented, } x & \text{Total cost (dollars), } y \\ \hline 1 & 1.50 \\ \hline 2 & 2.75 \\ \hline 3 & 4.00 \\ \hline 4 & 5.25 \\ \hline 5 & 6.50 \\ \hline \end{array} \][/tex]

Given that the relationship is linear, the total cost \( y \) can be modeled by the equation of a line:
[tex]\[ y = mx + b \][/tex]
where \( m \) is the slope (rate per night) and \( b \) is the y-intercept (initial cost when \( x = 0 \)).

To find the slope \( m \), we need to calculate the change in total cost (\( \Delta y \)) over the change in the number of nights rented (\( \Delta x \)):

First, calculate the differences between consecutive total costs (deltas):
[tex]\[ \begin{align*} \Delta y_1 &= 2.75 - 1.50 = 1.25 \\ \Delta y_2 &= 4.00 - 2.75 = 1.25 \\ \Delta y_3 &= 5.25 - 4.00 = 1.25 \\ \Delta y_4 &= 6.50 - 5.25 = 1.25 \\ \end{align*} \][/tex]

Similarly, calculate the differences between consecutive numbers of nights rented:
[tex]\[ \begin{align*} \Delta x_1 &= 2 - 1 = 1 \\ \Delta x_2 &= 3 - 2 = 1 \\ \Delta x_3 &= 4 - 3 = 1 \\ \Delta x_4 &= 5 - 4 = 1 \\ \end{align*} \][/tex]

Now, calculate the slope \( m \) by dividing \( \Delta y \) by \( \Delta x \):
[tex]\[ m = \frac{\Delta y}{\Delta x} = \frac{1.25}{1} = 1.25 \][/tex]

We obtained the same slope for each pair, indicating a constant rate per night and confirming the linear relationship.

So the slope \( m \) is 1.25 dollars per night.

This means:
- The rate per night for renting a movie is 1.25 dollars.
- The initial cost is given by the y-intercept \( b \), which we do not need to find for this problem since the question only pertains to the slope.

Hence, the correct statement is:
[tex]\[ \boxed{\text{D. The slope is 1.25. It represents the rate per night.}} \][/tex]