The 95% confidence interval for the population variance was found to be 5.21 to 19.20. However, we are to find a confidence interval for the population standard deviation. Recall that the standard deviation is the positive square root of the variance. Therefore, the confidence interval for the standard deviation can be found by taking the positive square root of the lower and upper bounds for the variance. Substitute these values to find the lower bound for the confidence interval of the population standard deviation, rounding the result to one decimal place. lower bound of G = V lower bound of oz Now find the upper bound for the confidence interval of the population standard deviation, rounding the result to one decimal place. upper bound of o = \\ upper bound of of Therefore, a 95% confidence interval for the population standard deviation is from a lower bound of to an upper bound of