Wildlife biologists monitor the ecological health of animals. For large animals whose habitat is hard to access, such as the Rocky Mountain elk, this can be a problem. Is it possible to reliably estimate the weight of an elk using the elk's chest girth? Here is a scatterplot showing x = chest girth (cm) and y = weight (kg) for 19 randomly selected Rocky Mountain elk, along with additional computer output for a least-squares regression line. The mean weight for these elk is 231 kg. (Context and data from Statistics, Learning from Data.)