Line of Best Fit Pre-Test

Latitude and longitude describe locations on the Earth with respect to the equator and prime meridian. The table shows the latitude and daily high temperatures on the first day of spring for different locations with the same longitude.

Temperature vs. Latitude
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|}
\hline \begin{tabular}{c}
Latitude \\
( N [tex]$)$[/tex]
\end{tabular} & 42 & 45 & 39 & 35 & 32 & 41 & 40 & 33 & 30 \\
\hline \begin{tabular}{c}
High Temp. \\
[tex]$\left({ }^{\circ} F \right)$[/tex]
\end{tabular} & 53 & 41 & 67 & 63 & 70 & 58 & 61 & 67 & 72 \\
\hline
\end{tabular}

Which statement describes the slope of the line of best fit for the data?

A. The temperature decreases by about [tex]$0.9^{\circ}$[/tex] for each 1 degree increase north in latitude.
B. The temperature decreases by about [tex]$1.7^{\circ}$[/tex] for each 1 degree increase north in latitude.
C. The temperature increases by about [tex]$0.8^{\circ}$[/tex] for each 1 degree increase north in latitude.
D. The temperature increases by about [tex]$1.3^{\circ}$[/tex] for each 1 degree increase north in latitude.

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Answer :

To find the slope of the line of best fit for the given data, we need to follow these steps:

1. Extract the Data: First, list the latitudes and the corresponding high temperatures.
- Latitudes ([tex]\(N^\circ\)[/tex]): 42, 45, 39, 35, 32, 41, 40, 33, 30
- High Temperatures ([tex]\(^{\circ} F\)[/tex]): 53, 41, 67, 63, 70, 58, 61, 67, 72

2. Understand the Relationship: We assume a linear relationship between the variables, latitude and temperature. The line of best fit seeks to best represent this relationship.

3. Calculate the Line of Best Fit: Using methods such as linear regression, the line of best fit can be calculated. The form of this linear equation is:
[tex]\[ \text{Temperature} = m \cdot \text{Latitude} + b \][/tex]
where [tex]\(m\)[/tex] is the slope of the line.

4. Interpret the Slope: The slope [tex]\(m\)[/tex] tells us the change in temperature for each one degree increase in latitude. A negative slope implies that temperature decreases as latitude increases, and vice versa.

5. Slope Calculation Result: After calculating the slope of the line of best fit for the provided data, we find that the slope is approximately [tex]\(-1.671\)[/tex].

6. Rounding the Slope: We round the slope to one decimal place, resulting in [tex]\(-1.7\)[/tex].

7. Choose the Correct Statement:
- A slope of [tex]\(-1.7\)[/tex] means the temperature decreases by approximately [tex]\(1.7^{\circ} F\)[/tex] for each 1 degree increase north in latitude.

Therefore, the statement that best describes the slope of the line of best fit for the data is:
- "The temperature decreases by about [tex]\(1.7^{\circ}\)[/tex] for each 1 degree increase north in latitude."