Question

answer neatly and correctly please!

According to the historical data, the life expectancy in Belgium is less than the life expectancy in the United States. A new study has been made to see whether this has changed. Records of 220 individuals from Belgium who died recently are selected at random. The 220 individuals lived a mean of 78.3 years with a standard deviation of 7.1 years. Records of 225 individuals from the United States who died recently are selected at random and independently. The 225 individuals lived a mean of 76.6 years with a standard deviation of 6.3 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 L1, L2, the difference between the life expectancy , in Belgium and the life expectancy , 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? x 6 ?

Answer 1

The statistic software output for this problem is:

Two sample Z summary confidence interval: Hi : Mean of population 1 (Std. dev. = 7.1) H2 : Mean of population 2 (Std. dev. = 6.3) P1 - H2 : Difference between two means 95% confidence interval results: Difference ni n2 Sample mean Std. err. L. limit U. limit Hi - 2 220 225 1.7 0.63681737 0.45186089 2.9481391

The 95% confidence interval is :

Lower limit = 0.45

Upper limit = 2.95