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A data set comparing a woman's shoe size to her height is represented by the table below.

[tex]\[
\begin{tabular}{|c|c|}
\hline
Shoe Size & Height (inches) \\
\hline
7.5 & 63 \\
\hline
9 & 72.5 \\
\hline
11 & 70 \\
\hline
7 & 62 \\
\hline
9 & 69.5 \\
\hline
10 & 72 \\
\hline
12 & 72.5 \\
\hline
13 & 73 \\
\hline
13 & 70 \\
\hline
\end{tabular}
\][/tex]

What is the equation for the line of best fit for a woman's height, [tex]\( y \)[/tex], based on her shoe size, [tex]\( x \)[/tex]?

A. [tex]\( y = 124x + 701 \)[/tex]
B. [tex]\( y = -1.24x - 70.1 \)[/tex]
C. [tex]\( y = 136x + 556 \)[/tex]
D. [tex]\( y = -1.36x - 55.6 \)[/tex]


Sagot :

To find the equation for the line of best fit representing a woman's height, [tex]\( y \)[/tex], based on her shoe size, [tex]\( x \)[/tex], let's proceed step by step.

Given a data set containing shoe sizes and corresponding heights, we aim to find a linear relationship between these variables. In a linear equation of the form [tex]\( y = mx + b \)[/tex]:
- [tex]\( m \)[/tex] is the slope of the line.
- [tex]\( b \)[/tex] is the y-intercept of the line.

### Step 1: Input the Data Points
The given data points are:
- [tex]\( (7.5, 63) \)[/tex]
- [tex]\( (9, 72.5) \)[/tex]
- [tex]\( (11, 70) \)[/tex]
- [tex]\( (7, 62) \)[/tex]
- [tex]\( (9, 69.5) \)[/tex]
- [tex]\( (10, 72) \)[/tex]
- [tex]\( (12, 72.5) \)[/tex]
- [tex]\( (13, 73) \)[/tex]
- [tex]\( (13, 70) \)[/tex]

### Step 2: Best Fit Line Calculation
The best fit line can be computed using the least squares method for linear regression, where the slope [tex]\( m \)[/tex] and y-intercept [tex]\( b \)[/tex] are determined.

From our calculated result:
- [tex]\( \text{slope, } m = 1.3604 \)[/tex]
- [tex]\( \text{intercept, } b = 55.558 \)[/tex]

### Step 3: Formulating the Equation
Using the calculated slope and intercept, we can write the linear equation as:
[tex]\[ y = 1.3604x + 55.558 \][/tex]

With some slight rounding and comparison to the given options, the equation is closest to the form:
[tex]\[ y = 1.36x + 55.6 \][/tex]

Thus, the correct equation for the line of best fit for a woman's height [tex]\( y \)[/tex], based on her shoe size [tex]\( x \)[/tex], is:
[tex]\[ y = 1.36x + 55.6 \][/tex]

### Conclusion
The correct answer is:
[tex]\[ y = 1.36x + 55.6 \][/tex]

Therefore, among the given options, the answer is:
[tex]\[ \boxed{y = 1.36x + 55.6} \][/tex]