Twenty-one adults were selected at random for a study of the effect of castor oil on the immune system. Participants took a certain amount of castor oil (x, in milliliters) each day for three months....

Twenty-one adults were selected at random for a study of the effect of castor oil on the immune system. Participants took a certain amount of castor oil (x, in milliliters) each day for three months. At the end of this regimen, the white blood cell count was measured (y, thousands of cells per microliter of blood) for each person. Analyze these data using any appropriate methods to determine whether there is a significant linear relationship between the amount of castor oil consumed and the number of white blood cells. Check the relevant assumptions. Assume that the more white blood cells, the stronger the immune system, and draw a conclusion about the effect of castor oil on the immune system.

Despite the rising cost of equipment, the number of fishing licenses issued in many states continues to increase. Officials are trying to predict the number of participants in freshwater fishing in order to hire and deploy the appropriate number of fish and game wardens. The data given on the website list the percentage of freshwater (x) and the freshwater fishing participation rate (y) by state.40 Note: No data are given for Hawaii. Analyze these data using any appropriate methods to determine whether there is a significant linear relationship between the percentage of freshwater and the participation rate. Check the relevant assumptions. Does the sign of b = 1 seem appropriate? Why or why not?