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 653.5 vehicles per hour, with a standard deviation of 311.7 vehicles per hour. a traffic engineer states that the mean improvement is between 581 and 726 vehicles per hour. with what level of confidence can this statement be made? express the answer as a percent and round to the nearest integer. the level of confidence is what % ?