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The table compares the average daily temperature and ice cream sales each day.

| Temperature (°F) | Ice Cream Sales ($) |
|------------------|---------------------|
| 61.0 | 107 |
| 60.3 | 116 |
| 64.2 | 120 |
| 66.4 | 122 |
| 71.3 | 125 |
| 73.9 | 130 |
| 74.2 | 132 |
| 75.2 | 135 |
| 80.1 | 151 |
| 84.8 | ??? |

What is the slope of the line of best fit, where [tex]\( x \)[/tex] represents the average daily temperature and [tex]\( y \)[/tex] represents the total ice cream sales? (Round your answer to one decimal place)

A. 6.3
B. 4.2
C. 2.8
D. 1.4


Sagot :

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

1. Data Collection:
- The given data for temperature (in degrees) and ice cream sales (in dollars) is as follows:
[tex]\[ \begin{array}{|c|c|} \hline \text{Temperature (ºF)} & \text{Ice Cream Sales (\$)} \\ \hline 61.0 & 107 \\ 60.3 & 116 \\ 64.2 & 120 \\ 66.4 & 122 \\ 71.3 & 125 \\ 73.9 & 130 \\ 74.2 & 132 \\ 75.2 & 135 \\ 80.1 & 151 \\ \hline \end{array} \][/tex]

2. Linear Regression Analysis:
- We will perform a linear regression analysis to find the best fit line [tex]\( y = mx + b \)[/tex] where [tex]\( m \)[/tex] is the slope and [tex]\( b \)[/tex] is the y-intercept.

3. Compute Slope and Y-Intercept:
- The slope (m) of the line of best fit is calculated using the formula:
[tex]\[ m = \frac{n(\sum xy) - (\sum x)(\sum y)}{n(\sum x^2) - (\sum x)^2} \][/tex]
- The y-intercept (b) can be found using:
[tex]\[ b = \bar{y} - m\bar{x} \][/tex]
where [tex]\( \bar{x} \)[/tex] and [tex]\( \bar{y} \)[/tex] are the means of the temperature and ice cream sales data respectively, and [tex]\( n \)[/tex] is the number of data points.

4. Given Results:
- The slope of the line of best fit (m) is approximately [tex]\( 1.7122883366705635 \)[/tex].
- When rounded to one decimal place, this result is [tex]\( 1.7 \)[/tex].

So, the slope of the line of best fit, rounded to one decimal place, is 1.7.