A student researcher compares the heights of American students and non-American students from the student body of a certain college in order to estimate the difference in their mean heights. A random sample of 18 American students had a mean height of 70 inches with a standard deviation of 3.03 inches. A random sample of 12 non-American students had a mean height of 66.1 inches with a standard deviation of 2.35 inches. Determine the 99 % confidence interval for the true mean difference between the mean height of the American students and the mean height of the non-American students. Assume that the population variances are equal and that the two populations are normally distributed. Step 3 of 3: Construct the 99 % confidence interval. Round your answers to two decimal places. Answer Tables Keypad How to enter your answer (opens in new window) Keyboard Shortcuts Previous Step Answers Lower endpoint Upper endpoint