Point spreads of NFL games. During the National Football League (NFL) season, Las Vegas od...

Point spreads of NFL games. During the National Football League (NFL) season, Las Vegas oddsmakers establish a point spread on each game for betting purposes. For exam pie, the Indianapolis Colts were established as 7-point favorites over the Chicago Bears in the 2007 Super Bowl. The final scores of NFL games were compared against the final point spreads established by the oddsmakers in Chance (Fall 1998). The difference between the outcome of the game and the point spread (called a point-spread error) was calculated for 240 NFL games. The mean and standard deviation of the point-spread errors are  and s = 13.3. Use this information to test the hypothesis that the true mean point-spread error for all NFL games is 0. Conduct the test at α = .01 and interpret the result.