scatterplots & lines of best fit\n1. what is the correlation of the graph below?\n2. draw a line of best fit…

scatterplots & lines of best fit\n1. what is the correlation of the graph below?\n2. draw a line of best fit for the points in the scatter graph.\n(3,2)(2,3)(4,5)(3,3)\n3. what is the correlation?\n4. use the line to predict the value of y when x = 12.\n5. what could be the y - intercept of the line of best fit?
Answer
Explanation:
Step1: Analyze the first scatter - plot
Visually, as x increases, y also tends to increase. So, the correlation is positive.
Step2: Draw the line of best - fit for given points
For points (3,2), (2,3), (4,5), (3,3), we can use the least - squares method conceptually. Plot the points on a graph and draw a line that seems to pass as close as possible to most of the points. In a more formal way, we can calculate the slope $m$ and y - intercept $b$ using formulas $m=\frac{n(\sum xy)-(\sum x)(\sum y)}{n(\sum x^{2})-(\sum x)^{2}}$ and $b = \bar{y}-m\bar{x}$ where $n$ is the number of data points, $\bar{x}$ and $\bar{y}$ are the means of $x$ and $y$ values respectively. But for a quick sketch, we can just eyeball it.
Step3: Determine the correlation for the second set of points
As x increases, y does not show a clear upward or downward trend. So, the correlation is weak or close to 0.
Step4: Predict y value when x = 12
After drawing the line of best - fit, we find the corresponding y - value on the line for x = 12. This requires having the equation of the line (either from a formal calculation or from the graph). If we assume the line equation is $y=mx + b$, we substitute $x = 12$ into it.
Step5: Estimate the y - intercept
The y - intercept is the value of y when x = 0. We look at where the line of best - fit intersects the y - axis.
Answer:
- Positive
- (Sketch the line as described above)
- Weak or close to 0
- (Value obtained from the line of best - fit for x = 12)
- (Value where the line of best - fit intersects the y - axis)