A researcher compares the effectiveness of two different instructional methods for teaching anatomy. A sample of 208 students using Method 1 produces a testing average of 86. A sample of 243 students using Method 2 produces a testing average of 52.7. Assume that the population standard deviation for Method 1 is 5.91, while the population standard deviation for Method 2 is 9.32. Determine the 99% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2. Step 1 of 3 : Find the point estimate for the true difference between the population means.