# Estimating Using Confidence Intervals

posted by
**Angela** on
.

An investor wants to determine the true average yield on a selection of investments from the Business week 1000. Suppose the investor draws a random sample of (n=40 firms) and finds an average yield on investment of (xbar = 5.00%) and a sample standard deviation (s = 1.50%). Construct a 95% confidence interval for the true average yield, using (s) as an estimate for the population standard deviation.