In 1990 the number of driver deaths per 100 000 for the different age groups was as follows ( Source : The National Highway Traffic Safety Administration's National Center for Statistics and Analysis ) Age Number of Driver Deaths per 100,090 15-24 25-39 40 - 69 70-79 80 + Table 12.2 a . For each age group , pick the midpoint of the interval for the * value . ( For the 80- group , use 85. ) Using " ages " as the independent variable and " Number of driver deaths per 190 ,000 " as the dependent variable , make a scatter plot of the data . Calculate the least squares ( best - fit line . Put the equation in the form of : y - a t bx d . Find the correlation coefficient Is it significant R . Pick two ages and find the estimated fatality rates E . Use the two points in ( e ) to plot the least squares line on your graph from ( 6 ) 5 . Based on the above data is there a linear relationship between age of a driver and driver fatality rate ? . What is the slope of the least squares ( best -fit ) line ? Interpret the slope