Answer:
a)
b) r =-0.932
The % of variation is given by the determination coefficient given by and on this case
, so then the % of variation explained by the linear model is 86.87%.
Step-by-step explanation:
Assuming the following dataset:
Monthly Sales (Y) Interest Rate (X)
22 9.2
20 7.6
10 10.4
45 5.3
Part a
And we want a linear model on this way y=mx+b, where m represent the slope and b the intercept. In order to find the slope we have this formula:
Where:
With these we can find the sums:
And the slope would be:
Nowe we can find the means for x and y like this:
And we can find the intercept using this:
So the line would be given by:
Part b
For this case we need to calculate the correlation coefficient given by:
So then the correlation coefficient would be r =-0.932
The % of variation is given by the determination coefficient given by and on this case
, so then the % of variation explained by the linear model is 86.87%.