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A construction manager is monitoring the progress of building a new house. The scatterplot and table below show the number of months since the start of the build and the percentage of the house still left to build. A linear function can be used to model this relationship.

[tex]
\[
\begin{tabular}{|c|c|}
\hline
\begin{tabular}{c}
Number of \\
Months Since \\
Start of Build, $x$
\end{tabular}
&
\begin{tabular}{c}
Percentage of \\
House Left \\
to Build, $y$
\end{tabular} \\
\hline
0 & 100 \\
\hline
1 & 86 \\
\hline
2 & 65 \\
\hline
3 & 59 \\
\hline
4 & 41 \\
\hline
5 & 34 \\
\hline
\end{tabular}
\]
[/tex]

Which function best models the data?

A. [tex]y = -13.5x + 97.8[/tex]

B. [tex]y = -13.5x + 7.3[/tex]

C. [tex]y = 97.8x - 13.5[/tex]

D. [tex]y = 7.3x - 97.8[/tex]

Answer :

We begin with the given data points for the number of months since the start of the build ([tex]$x$[/tex]) and the percentage of the house left to build ([tex]$y$[/tex]):

[tex]$$
\begin{array}{cc}
x & y \\
\hline
0 & 100 \\
1 & 86 \\
2 & 65 \\
3 & 59 \\
4 & 41 \\
5 & 34 \\
\end{array}
$$[/tex]

Since a linear function of the form

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

is to be used to model this relationship, we need to determine the slope ([tex]$m$[/tex]) and the [tex]$y$[/tex]-intercept ([tex]$b$[/tex]).

### Step 1. Calculate the Slope

The slope is given by the formula

[tex]$$
m = \frac{n\sum xy - (\sum x)(\sum y)}{n\sum x^2 - (\sum x)^2},
$$[/tex]

where [tex]$n$[/tex] is the number of data points.

1. There are [tex]$n = 6$[/tex] data points.
2. The sums needed are:
- [tex]$\sum x = 0 + 1 + 2 + 3 + 4 + 5$[/tex]
- [tex]$\sum y = 100 + 86 + 65 + 59 + 41 + 34$[/tex]
- [tex]$\sum (xy)$[/tex] is the sum of the product of each pair [tex]$(x,y)$[/tex].
- [tex]$\sum (x^2)$[/tex] is the sum of the squares of [tex]$x$[/tex].

By substituting and calculating, we determine that the slope is approximately

[tex]$$
m \approx -13.457.
$$[/tex]

### Step 2. Calculate the [tex]$y$[/tex]-intercept

The [tex]$y$[/tex]-intercept is given by

[tex]$$
b = \frac{\sum y - m\sum x}{n}.
$$[/tex]

Using the previously calculated slope and appropriate sums, we find that

[tex]$$
b \approx 97.810.
$$[/tex]

### Step 3. Compare with the Given Options

The candidate functions given are:

1. [tex]$\displaystyle y = -13.5x + 97.8$[/tex]
2. [tex]$\displaystyle y = -13.5x + 7.3$[/tex]
3. [tex]$\displaystyle y = 97.8x - 13.5$[/tex]
4. [tex]$\displaystyle y = 7.3x - 97.8$[/tex]

Our calculated slope of approximately [tex]$-13.457$[/tex] and [tex]$y$[/tex]-intercept of approximately [tex]$97.810$[/tex] closely match the values in option 1, which is

[tex]$$
y = -13.5x + 97.8.
$$[/tex]

### Conclusion

Since the computed values are nearly identical to those in the first candidate function, the linear function that best models the data is:

[tex]$$
\boxed{y=-13.5x+97.8.}
$$[/tex]

Thank you for reading the article A construction manager is monitoring the progress of building a new house The scatterplot and table below show the number of months since the start. We hope the information provided is useful and helps you understand this topic better. Feel free to explore more helpful content on our website!

Rewritten by : Jeany