According to the historical data, the life expectancy in Germany is less than the life expectancy in the United States. A new study has been made to see whether this has changed. Records of 290 individuals from Germany who died recently are selected at random. The 290 individuals lived a mean of 77.9 years with a standard deviation of 6.8 years. Records of 245 individuals from the United States who died recently are selected at random and independently. The 245 individuals lived a mean of 76.6 years with a standard deviation of 7.1 years. Assume that the population standard deviations of lifetimes in these two countries can be estimated by the sample standard deviations, as the samples used were quite large. Construct a 95% confidence interval for u1-u2 , the difference between the life expectancy u1 in Germany and the life expectancy u2 in the United States. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places.
What is the lower limit of the 95% confidence interval?
What is the upper limit of the 95% confidence interval?