A researcher compares the effectiveness of two different instructional methods for teaching anatomy. A sample of 146 Students using Method 1 Produces a testing average of 51.6. A sample of 180 students using Method 2 produces a testing average of 62.7. Assume the standard deviation is known to be 9.42 for method 1 and 14.5 for method 2. Determine the 98% confidence interval for the true difference between testing averages for students using method 1 and students using method 2. Find the critical value that should be used in constructing the confidence interval, and the lower and upper endpoint.