11.51 The data file Trading Stocks shows percentage changes (xi) in a stock market over the first five trading days of each of 11 years and also the corresponding percentage changes (yi) in the index over the whole year. If the stock market increases by 3.0% in the first five trading days of a year, find 95% confidence intervals for the actual and also the expected percentage changes in the index over the whole year.

Discuss the distinction between these intervals.