High-power experimental engines are being developed by the Stevens Motor Company for use in its new sports coupe. The engineers have calculated the maximum horsepower for the engine to be680HP

680

HP

. Sixteen engines are randomly selected for horsepower testing. The sample has an average maximum HP of650

650

with a standard deviation of50HP

50

HP

. Assume the population is normally distributed.

Step 1 of 2:Calculate a confidence interval for the average maximum HP for the experimental engine. Use a significance level of=0.05

=

0.05

. Round your answers to two decimal places.