Georges asked five of his friends how long they studied for the last math test and what grade they received. he found a linear regression equation for the data to be y = 9.6x + 65.8. what does the 65.8 mean in the context of this equation? a) if they studied 0 hours they would earn a 65.8. b) the lowest grade of his five friends was a 65.8. c) the lowest grade they could receive on the test was a 65.8. d) for every hour they studied their grade would go up 65.8 points.