y = 0.34x - 0.9 (Option A)
We are given the data and we want to find the line of best fit.
The line of best fit is a line that goes through the data points and it gives the best representation of the spread of the data.
The equation of a line is given as:
y = mx + c
y represents y-values
x represents x-values
m is the slope of the line
c is the y-intercept of the line or where the line crosses the y-axis.
To get this equation for this question, we need to find both m and c.
In order to do this, the formulas are given below:
[tex]\begin{gathered} M=\frac{\sum(x_i-\bar{\bar{X})(y_i-\bar{Y)}}}{\sum(x_i-\bar{X)^2}} \\ \text{where M is slope} \\ x_i=\text{ individual data points of x} \\ X=\operatorname{mean}\text{ of x values} \\ Y=\text{ mean of y values} \end{gathered}[/tex]While for c or the y-intercept, we have:
[tex]\begin{gathered} c=\bar{Y}-m\bar{X} \\ \text{where Y and X retain their same meaning from before} \end{gathered}[/tex]Before we can calculate m and c, we need to calculate the means of both x and y values give to us.
This is done below:
[tex]\begin{gathered} \operatorname{mean}=\frac{\sum x_i}{n} \\ \\ \bar{Y}=\frac{0.5+0.6+0.8+0.9+1.2}{5}=0.8 \\ \bar{X}=\frac{4+4.5+5+5.5+6}{5}=5 \end{gathered}[/tex]Now we can proceed to get the slope m of our line.
In order to be tidy, we shall use a table to solve. This table is shown in the image below:
Thus, we can now calculate our slope m:
[tex]\begin{gathered} M=\frac{\sum(x_i-\bar{\bar{X})(y_i-\bar{Y)}}}{\sum(x_i-\bar{X)^2}} \\ \\ M=\frac{(-1)(-0.3)+(-0.5)(-0.2)+0(0)+(0.5)(0.1)+(1)(0.4)}{1+0.25+0+0.25+1} \\ \\ M=\frac{0.3+0.1+0+0.05+0.4}{2.5}=0.34 \end{gathered}[/tex]Therefore the slope (m) = 0.34
Now to calculate intercept (c)
[tex]\begin{gathered} c=\bar{Y}-m\bar{X} \\ \bar{Y}=0.8\text{ (from previous calculation above)} \\ \bar{X}=5\text{ (from previous calculation above)} \\ \\ c=0.8-0.34\times5 \\ c=0.8-1.7=-0.9 \end{gathered}[/tex]Therefore, the intercept (c) = - 0.9
Bringing it all together, we can write the equation of the line as:
y = 0.34x - 0.9
Therefore the answer is: y = 0.34x - 0.9 (Option A)
