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 653.2 vehicles per hour, with a standard deviation of 311.7 vehicles per hour. a)Approximately what sample size is needed so that a 95% confidence interval will specify the mean to within ±55 vehicles per hour? b)Approximately what sample size is needed so that a 98% confidence interval will specify the mean to within ±55 vehicles per hour? c)In a sample of 50 electric motors, the average efficiency (in percent) was 85 and the standard deviation was 2. Find a 95% confidence interval for the mean efficiency. Round the answers to three decimal places.
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
a)Approximately what
b)Approximately what sample size is needed so that a 98% confidence interval will specify the mean to within ±55 vehicles per hour?
c)In a sample of 50 electric motors, the average efficiency (in percent) was 85 and the standard deviation was 2. Find a 95% confidence interval for the mean efficiency. Round the answers to three decimal places.
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