STA 2023 Lecture Notes - Lecture 17: Confidence Interval, Standard Deviation, Point Estimation
Document Summary
Section 7. 2 estimating mean when standard deviation is unknown. When performing any type of test or analysis using z-score, it is required that population standard deviation is already known. In real life, this is hardly ever the case. It is almost always impossible for us to know the standard deviation of the population from which our sample is drawn. Find the critical value for a 99% confidence level for a t distribution with a sample size: n=5. Construct a 90% confidence interval for the mean age at which a baby first crawls. For a simple random sample of forty 2007 ford mustangs the mean gas mileage was. 20 miles per gallon with standard deviation of 1. 5 miles per gallon. Construct a 95% confidence interval for the mean gas mileage of similar 2007 ford mustangs. Step 3: find the critical value that corresponds to the confidence level. Step 4: find the margin of error e.
