To estimate sigma: (squareroot (n - 1) s^2/chi_alpha/2^2, squareroot (n - 1 s^2/chi_1 - alpha/2)^2) = (s squareroot (n - 1/squareroot chi_alpha/2^2, s squareroot (n - 1)/squareroot chi_(1 - alpha/2)^2) Note that the "square" on chi^2 is part of the symbol, so squareroot chi^2 notequalto chi, in other words do not squareroot the chi^2 values in the standard deviation formula. Unfortunately, the TI Calculator does not have a way to perform these confidence intervals unless we program them ourselves. So, I will give you the appropriate chi_alpha/2^2 and chi_(1 - alpha/2)^2, whereas usually you have to look up the values on a table. The sample standard deviation of the sale price of 12 randomly selected three year old Chevy Corvette is $2615.19. In this case, with a 90% confidence level and a degree of freedom of 11 (since df = n - 1 = 12 - 1 = 11), chi_(1 - alpha/2)^2 = 4.575 and chi_alpha/2^2 = 19 675. Construct and interpret a 90% confidence interval for the population variance. Construct and interpret a 90% confidence interval for the population standard deviation.