Confidence Intervals - Introduction to Statistics | STAT 1222, Assignments of Statistics

Download Confidence Intervals - Introduction to Statistics | STAT 1222 and more Assignments Statistics in PDF only on Docsity! Confidence Intervals Stat 1222 (Professor: Dr. A. Biswas) 3/3/09 1. Starting salaries of 50 randomly selected college graduates in US who have taken a statistics course has a mean of $42,786 and a standard deviation of $8,912. Construct a 97% confidence interval for the mean starting salary for college graduates in US who have taken a statistics course. Also, report the critical value zc corresponding to a confidence level of c = .97. 2. Suppose you want to obtain an estimate of the mean caffeine content in a cup of coffee correct to within 3 mg and with 80 % confidence. Find the minimum sample size necessary to estimate the mean caffeine content in a cup of coffee. Assume that the population is normally distributed with a standard deviation of 30. 3. An economist wants to estimate the mean income during the first year of employment for a college graduate. Find the minimum sample size needed to estimate the mean µ with 95% confidence. The estimate must be accurate to within $500 of µ. Assume σ = $6250.