The weight (in pounds) and height (in inches) for a child were measured every few months over a two-year period. The results are given in the table.

\begin{tabular}{|l|c|c|c|c|c|c|c|c|c|}
\hline
Weight [tex]$(x)$[/tex] & 8 & 12 & 18 & 24 & 30 & 32 & 35 & 37 & 40 \\
\hline
Height [tex]$(y)$[/tex] & 22 & 23 & 26 & 30 & 32 & 33 & 35 & 36 & 38 \\
\hline
\end{tabular}

Using technology, what is the [tex]$y$[/tex]-intercept and what is its interpretation?

A. The [tex]$y$[/tex]-intercept is 17.37. When the weight is 0 pounds, the height will be 17.37 inches.
B. The [tex]$y$[/tex]-intercept is -34.13. When the weight is 0 pounds, the height will be -34.13 inches.
C. The [tex]$y$[/tex]-intercept is 17.37. When the weight is 0 pounds, it does not make sense to interpret the height.
D. The [tex]$y$[/tex]-intercept is -34.13. When the weight is 0 pounds, the height is predicted to be -34.13 inches.



Answer :

Let's solve this step-by-step:

1. Record the Given Data:

The weight (in pounds) and height (in inches) are given in the table:

[tex]\[ \begin{array}{|c|c|c|c|c|c|c|c|c|c|} \hline Weight~(x) & 8 & 12 & 18 & 24 & 30 & 32 & 35 & 37 & 40 \\ \hline Height~(y) & 22 & 23 & 26 & 30 & 32 & 33 & 35 & 36 & 38 \\ \hline \end{array} \][/tex]

2. Determine the Linear Regression Line:

By using appropriate technology, we perform a linear regression analysis on the data. The linear regression line is given by the equation:

[tex]\[ y = mx + b \][/tex]

where [tex]\(m\)[/tex] is the slope of the line and [tex]\(b\)[/tex] is the y-intercept.

3. Find the Slope (m) and Intercept (b):

Using the given data and performing the regression analysis, we get the y-intercept ([tex]\(b\)[/tex]).

4. Identify the y-Intercept:

The y-intercept ([tex]\(b\)[/tex]) is a specific value that the technology calculates. This value tells us where the line crosses the y-axis, i.e., the value of [tex]\(y\)[/tex] when [tex]\(x = 0\)[/tex].

5. Interpret the y-Intercept:

In the context of this problem, when [tex]\(x = 0\)[/tex] (weight is 0 pounds), the height [tex]\(y\)[/tex] will be equal to the y-intercept value.

6. Result and Interpretation:

The result from our regression analysis gives us a y-intercept of 17.37.

Therefore, when the weight is 0 pounds, the height will be 17.37 inches.

Given the options provided:

- The [tex]$y$[/tex]-intercept is 17.37. When the weight is 0 pounds, the height will be 17.37 inches.
- The [tex]$y$[/tex]-intercept is -34.13. When the weight is 0 pounds, the height will be -34.13 inches.
- The [tex]$y$[/tex]-intercept is 17.37. When the weight is 0 pounds, it does not make sense to interpret the height.
- The [tex]$y$[/tex]-intercept is -34.13. When the weight is 0 pounds, the height is predicted to be -34.13 inches.

The correct answer is:

The [tex]$y$[/tex]-intercept is 17.37. When the weight is 0 pounds, the height will be 17.37 inches.