Now, the same researcher in Question 1 is about to estimate the average life expectancy for Wisconsinites from a sample of 50 Wisconsinites. From the same sample, she still finds that the average life expectancy is 76.7. For this time, however, she has no information about the population standard deviation. Construct a 95% confidence interval for the mean life expectancy of all Wisconsinites (Hint: See the recording of Exercise 1 on slide 14 in the part 2 lecture. Format of a confidence interval is x bar t_0.025,49 s/n . Calculate the lower and upper limit numbers in Excel.)