1) Suppose that 64 smokers were sampled. Assume the sample mean and the sample standard deviation remained the same ($20 and $5, respectively).
a. What is the 95% confidence interval estimate of u?
b. A research a firm a conducted a survey to determine the mean amount of steady smokers spend on cigarettes during a week. A sample of 49 steady smokers revealed that X = $20 and s= $5. What is the 95% confidence interval estimate of u?
Explain why this confidence interval is narrower than the one determined in the previous exercise.