An article presents a new method for timing traffic signals in heavily traveled intersections. The effectiveness of the new method was evaluated in a simulation study. In 50 simulations, the mean improvement in traffic flow in a particular intersection was 656.2 vehicles per hour, with a standard deviation of 314.7 vehicles per hour. a) Find a 95% upper confidence bound for the mean improvement. (Round the final answer to three decimal places.) The 95% upper confidence bound for the mean improvement is. b) Find a 98% lower confidence bound for the mean improvement. (Round the final answer to three decimal places.) The 98% lower confidence bound for the mean