The scores on an examination in economics are approximately normally distributed with mean 500 and an unknown standard deviation. The following random sample of scores from this examination. 429, 431, 485, 511, 555, 571, 601 Send data to calculator Send data to Excel Find a 99% confidence interval for the population standard deviation. Then give its lower limit and upper limit. Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places. (If necessary, consult a list formulas.) Lower limit: X 5 ? Upper limit