The plot below is a very simple k-nn regression example, where the black dots are the data observations and the blue line is the predictions from a k-nn regression model created from this data where k=2.

Using the formula for RMSE (given in the reading), and the graph below, by hand (pen and paper or use R as a calculator) calculate RMSE for this model. Use one decimal place of precision when inputting the heights of the black dots and blue line.