A student researcher compares the ages of cars owned by students and cars owned by faculty at a local state college. A sample of 228 cars owned by students had an average age of 8.2 years. A sample of 222 cars owned by faculty had an average age of 5.83 years. Assume that the population standard deviation for cars owned by students is 3.36 years, while the population standard deviation for cars owned by faculty is 3.27 years. Determine the 90% confidence interval for the difference between the true mean ages for cars owned by students and faculty. Step 1 of 3 : Find the point estimate for the true difference between the population means.