College

A construction manager is monitoring the progress of the build of a new house. The scatterplot and table 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.

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

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 :

To solve this problem, we need to determine which linear function best fits the given data. Let's follow these steps:

1. Identify the Data Points:
- Number of months since the start of the build ([tex]\(x\)[/tex]): [0, 1, 2, 3, 4, 5]
- Percentage of the house left to build ([tex]\(y\)[/tex]): [100, 86, 65, 59, 41, 34]

2. Look for a Linear Relationship:
A linear function is generally of the form [tex]\(y = mx + b\)[/tex], where:
- [tex]\(m\)[/tex] is the slope.
- [tex]\(b\)[/tex] is the y-intercept.

3. Calculate the Slope ([tex]\(m\)[/tex]):
Use the formula for the slope between two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex]:
[tex]\[
m = \frac{y_2 - y_1}{x_2 - x_1}
\][/tex]

Calculate the slope using the data from two points. Let's use points (0, 100) and (1, 86):
[tex]\[
m = \frac{86 - 100}{1 - 0} = \frac{-14}{1} = -14
\][/tex]
Let's take a few more averages to notice that the over-average slope estimated from multiple points seems to justify a slope of around [tex]\(-13.5\)[/tex], not exactly from the data we calculated but closely matching the provided option.

4. Find the Y-intercept ([tex]\(b\)[/tex]):
To find the y-intercept, plug one of the points and the slope back into the line equation. Using point (0, 100):
[tex]\[
b = y - mx = 100 - (-13.5 \times 0) = 100
\][/tex]
Again, with adjustments and evaluating the closeness of fit, an intercept closely aligned to the choices is 97.8, as we see in real placeholders.

5. Compare with Given Functions:
The function options are:
- [tex]\(y = -13.5x + 97.8\)[/tex]
- [tex]\(y = -13.5x + 7.3\)[/tex]
- [tex]\(y = 97.8x - 13.5\)[/tex]
- [tex]\(y = 7.3x - 97.8\)[/tex]

Comparing our calculated values to these, the function [tex]\(y = -13.5x + 97.8\)[/tex] appears to be the closest match.

Therefore, the function that best models the data from the table is:
[tex]\[ y = -13.5x + 97.8 \][/tex]

Other Questions