4. ( 12 points) Because elderly people may have difficulty standing to have their heights measured, a study looked at predicting overall height from height to just the knee (in centimeters). The equation of the least-squares regression line for predicting the height of a person from his knee height is: height = 42.93 + (2.45 x knee height) a) What does the slope of 2.45 mean in the context of this problem? b) By looking at the least-squares regression line, you can see that the correlation between knee height and overall height is: a. Greater than zero b. Less than zero c. Unable to be determined without seeing the data and scatterplot. c) Use this to predict the height of a person with a knee height of 50 cm. d) When using a regression line for prediction, you should avoid extrapolation. What does this mean or give an example using this particular study. 2