The number of houses sold in Miami Springs and the average monthly mortgage rates for 18 months randomly selected between January 2011 and April 2013 are shown in the following table. Mortgage rate (%) 7.5 9.0 7.0 10.5 10.0 9.5 8.5 10.0 11.0 a. b. Number of houses sold 90 72 89 62 58 70 74 65 51 Mortgage rate Number of houses sold (%) 9.5 6.5 8.0 9.0 10.5 9.5 11.0 7.5 8.5 68 97 79 75 53 73 50 82 70 Draw a scatter diagram with the number of houses sold on the vertical axis. Describe the relationship between mortgage rate and number of houses sold.