20.Exercise 4 (page 278) gives data on concentration (in parts per million) over time.
Use a calculator or spreadsheet software such as Excel to find the correlation r (refer to Spotlight 6.2 on page 259). Explain from looking at the scatterplot why this value of r is reasonable.
Suppose that the concentration had been recorded in parts per billion instead of parts per million. For example, the value 354.16 would become 354,160. How would the value of r change?