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 12 American students had a mean height of 70.2 inches with a standard deviation of 2.73 inches. A random sample of 18 non-American students had a mean height of 66.9 inches with a standard deviation of 3.13 inches. Determine the 98 % 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 98 % confidence interval. Round your answers to two decimal places. Answer Tables Keypad How to enter your answer (opens in new window) Keyboard Shortcut Previous Step Answers Lower endpoint: Upper endpoint