Drilling down beneath a lake in Alaska yields chemical evidence of past changes in climate. Biological silicon, left by the skeletons of single-celled creatures called diatoms, measures the abundance of life in the lake. A rather complex variable based on the ratio of certain isotopes relative to ocean water gives an indirect measure of moisture, mostly from snow. As we drill down, we look farther into the past. Here are data from 2300 to 12,000 years ago: Isotope (%) Silicon (mg/g) Isotope (%) Silicon (mg/g) Isotope (%) Silicon (mg/g)
-19.90 95 -20.71 154 -21.63 222
-19.84 104 -20.80 263 -21.63 233
-19.46 116 -20.85 267 -21.19 185
-20.20 139 -21.28 294 -19.37 339

Required:
a. Find the single outlier in the data. This point strongly influences the correlation. What is the correlation with this point?
b. Is the outlier also strongly influential for the regression line? Calculate the regression line with the outlier.