Suppose the speeds of vehicles traveling on a highway are normally distributed and have a known population standard deviation of 4 miles per hour and an unknown population mean. A random sample of 21 vehicles is taken and gives a sample mean of 61 miles per hour. Find the confidence interval for the population mean with a 98% confidence level.

z0.10z0.10	z0.05z0.05	z0.025z0.025	z0.01z0.01	z0.005z0.005
1.282	1.645	1.960	2.326	2.576

You may use a calculator or the common z values above.

• Round the final answer to twodecimal places.