Chapter 7 Practice 1 Answer the following questions by showing all necessary work and using complete sentences. 1.) After conducting a survey of his students, a professor reported that "There appears to be a strong correlation between grade point average and whether or not a student works." Comment on this observation. Answer (Think: what are the variables, what kind of variables are they ?) Coordinates measure strength between quantitative variables whether a student works or not is categorical coordinates cannot be used. 2.) The following scatterplot shows a relationship between x and y that results in a correlation coefficient of r = 0, Explain why r = 0 in this situation even though there appears to be a strong relationship between the x and y variables Answer (What kind of relationship should the scafter plot have to measure correlation) 3.) The following scatterplot shows the relationship between the time (in seconds) it look men to run the 1500m race for the gold medal and the year of the Olympics that the race was run in: Question Answer a. Write a few sentences desonbing the association. Think: Direction, Shape, and Strength. Then, explain how these in context with the two variables. Finish by mentioning any outliers) b. Estimate the correlation. Use the strength and direction to do sol 4.) Identify what is wrong with each of the following statements: "What properties of correlation are incorrect in each situation) Question Answer The correlation between Olympic gold medal times for the 800m hurdles and year is -0.66 seconds per year. b. The correlation between Olympic gold medal times for the 100m dash and year is -1.37. Since the correlation between Olympic gold medal times for the 800m hurdles and 100m dash is -0. 41, the correlation between times for the 100m dash and the 800m hurdles is + 0.41