Part II - Free Response 1. Suppose a high school guidance counselor wants to find out the proportion of students at his high school who this study. (2 pts) have tried alcohol. He sends out an email to 200 randomly chosen students asking them if they have tried alcohol. Of the 92 that responded, 6% said they had tried alcohol. State the 2 types of biases that occurred in 2. A random sample of 200 patients is taken from a large medical clinic and each is classified as to whether or not they took an omega-3 fish oil tablet daily. It was found that those who consumed an omega-3 tablet every day had lower cholesterol levels than those who did not. (a) Is this an experiment or an observational study? Explain (1 pt) (b) Explain how confounding variables may affect the results of the study. (1 pt) (c) It was found that there was a statistically significant difference in cholesterol levels between those who took omega-3 fish oil tablet every day and those who did not. Can we generalize the results to all patients at the large medical clinic? (1 pt) (d) Can we conclude that taking an omega-3 fish oil tablet every day causes a reduction in cholesterol levels? Explain your reasoning. (1 pt) 3. Twenty-five students were randomly selected and asked "How many hours of TV did you watch this weekend?" The sample mean for the data is x = 5 hours. The dot plot below shows the distribution of the sample mean hours of TV watched for 500 random samples of size 25 taken with replacement from the original sample. 45 Simulated sample mean 5.5 (a) Use the results of the simulation to approximate the margin of error for the estimate of the mean number of hours of television watched. (1 pt) Distribution of Simulated Mean = samples mean SD 500 4.969 0.28 (b) Interpret the margin of error. (2 pts)