The medical researcher from nation institute of health has gathered samples on life expectancies of people who are longtime smokers and those who are nonsmokers. Smokers with 50 sample size , sample mean 67.6 years and sample standard deviation of 5 years. Nonsmokers with a 60 sample size m sample mean of 74.5 yrs and a sample standard deviation of 3.5 yrs. Compute a 95 confidence interval for the mean life expectancy of a smoker ? Compute a 95% confidence interval for the mean life expectancy of a non smoker. Do these two confidence intervals provide convicting evidence that nonsmokers live longer on the average than do smokers? Explain