Acid rain Researchers studying acid rain measured the acidity of precipitation in a Colorado wilderness area for 150 consecutive weeks. Acidity is measured by pH. Lower pH values show higher acidity. The researchers observed a linear pattern over time.

They reported that the regression line pH = 5.43 −

0.0053(weeks) fit the data well.19

(a) Identify the slope of the line and explain what it means in this setting.

(b) Identify the y intercept of the line and explain what it means in this setting.

(c) According to the regression line, what was the pH at the end of this study?