The typing speeds of professional typists are normally distributed with a population standard deviation of 4 characters and an unknown population mean. A random sample of 65 professional typists is taken and results in a sample mean speed of 33 characters per minute. Identify the parameters needed to calculate a confidence interval at the 99% confidence level. Then find the confidence interval. z0.10 z0.05 z0.025 z0.01 z0.005 1.282 1.645 1.960 2.326 2.576 You may use a calculator or the common z values above. Round each number to three decimal places, if necessary. Provide your answer below: $\overline{x}\ =\ $x = $\sigma\ =\ $ = $n\ =\ $n = $z_{\frac{\alpha}{2}}\ =\ $z 2 = (, )