The data below show, for a consumer finance company operating in six cities, the number of competing loan companies operating in the city (X) and the number per thousand of the company's loans made in that city that are currently delinquent (Y):
i 1 2 3 4 5 6
Xi 4 1 2 3 3 4
Yi 16 5 10 15 13 22
(a) What is the 90% confidence interval for σ?
(b) Find the 95% prediction interval for the average number of loads in two cities, if the finance company is having two more offices in two cities which each has 3 competing loan companies.