please post how you come to answer

The Ishaces Bond Index fund (TLT) has a mean (average) and annual standard deviation of realized returns of 9% and 10%, respectively. If these are unbiased estimators of expected returns and future volatility, answer the following. (Round your answers to the nearest Integer.) (a) What is the 68% confidence interval for the returns on TLT next year (as a percent)? to9 What is the 95% confidence interval for the returns on TLT next year (as a percent)? % to What is the 99.7% confidence interval for the returns on TLT next year (as a percent)? toe