Question: When nicotine is absorbed by the body, cotinine is produced. A measurement of cotinine in the body is therefore a good indicator of how much a person smokes. Listed below are the reported number of cigarettes smoked per day and the measured amounts of cotinine (in ng/ml). (The values are from randomly selected subjects in a National Health Examination Survey.)

Is there a significant linear correlation?

How would you measure the cotinine level in the body?

Explain the result.