Two machines are designed to fill cans with 1 pound of ground coffee. Assume the standard deviations of fill weights for the machines are known to be 0.20 oz for machine 1 and 0.25 oz for machine 2. Independent random samples of cans are selected from the two machines. Twenty-five cans were selected from machine 1 and yielded an average weight of 15.96 oz. Twenty cans were selected from machine 2 and yielded an average of 15.67 oz. A confidence interval calculated to estimate the difference in the mean fill weights produced by the two machines is (0.155, 0.424). What is the confidence level