In order to find the life expectancy of the picture tubes of particular brand of portable televisions, a sample of 6 tubes was selected randomly. The sample revealed following life expectancies.
Picture Tube: 1, 2, 3, 4, 5, 6
Life Expectancy (Xi) (In thousands of hours): 8.2, 7.5, 9.5, 6.5, 8.5, 7.8
Give a 90% confidence interval estimate for the life expectancy of all picture tubes for this brand of portable televisions. Suppose the population is basically distributed.