Pretest: Analyzing Data Sets

Using the data below, determine the relationship between the total sales and daily earnings.

\begin{tabular}{|r|r|}
\hline
Total Sales (\[tex]$) & Daily Earnings (\$[/tex]) \\
\hline
0 & 80 \\
\hline
200 & 110 \\
\hline
500 & 155 \\
\hline
800 & 200 \\
\hline
1,200 & 260 \\
\hline
\end{tabular}

1. The equation that gives Ashley's daily earnings based on her total sales is [tex]$\square$[/tex].
2. When this data is plotted on a graph with a line connecting all the points, the [tex]$y$[/tex]-intercept of the line represents [tex]$\square$[/tex].
3. In this scenario, the [tex]$y$[/tex]-intercept is [tex]$\square$[/tex].
4. The slope of the equation is [tex]$\square$[/tex].



Answer :

Sure, let's work through the problem step by step using the data provided about Alyssa's daily earnings and total sales.

Given the table:
[tex]\[ \begin{array}{|r|r|} \hline \text{Total Sales (x)} & \text{Daily Earnings (y)} \\ \hline 0 & 80 \\ \hline 200 & 110 \\ \hline 500 & 155 \\ \hline 800 & 200 \\ \hline 1200 & 260 \\ \hline \end{array} \][/tex]

To determine the equation of the line that represents Alyssa's daily earnings [tex]\( y \)[/tex] based on her total sales [tex]\( x \)[/tex], follow these steps:

1. Identify two points to calculate the slope:
- The first point is (0, 80).
- The second point is (1200, 260).

2. Calculate the slope (m) using the formula for slope between two points [tex]\((x1, y1)\)[/tex] and [tex]\((x2, y2)\)[/tex]:
[tex]\[ m = \frac{y2 - y1}{x2 - x1} \][/tex]
Substituting the provided points:
[tex]\[ m = \frac{260 - 80}{1200 - 0} = \frac{180}{1200} = 0.15 \][/tex]

3. Determine the y-intercept (b), which is the value of [tex]\( y \)[/tex] when [tex]\( x = 0 \)[/tex].
- In this case, the first point directly gives us the y-intercept because [tex]\( x = 0 \)[/tex] and [tex]\( y = 80 \)[/tex].

4. Formulate the equation of the line which goes through these points. The general form of the linear equation is:
[tex]\[ y = mx + b \][/tex]
Substituting the slope (m) and the y-intercept (b):
[tex]\[ y = 0.15x + 80 \][/tex]

Summarizing these steps and filling in the blanks for the question:

1. The equation that gives Alyssa's daily earnings based on her total sales is:
[tex]\[ y = 0.15x + 80 \][/tex]

2. When this data is plotted on a graph with a line connecting all the points, the slope of the equation is:
[tex]\[ 0.15 \][/tex]

3. The y-intercept of the line represents Alyssa's initial daily earnings (when total sales are zero), which in this scenario is:
[tex]\[ 80 \][/tex]