A researcher compares the effectiveness of two different instructional methods for teaching anatomy. A sample of 158 students using Method 1 produces a testing average of 67.5. A sample of 179 students using Method 2 produces a testing average of 55.2. Assume the standard deviation is known to be 17.81 for Method 1 and 19.32 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.