The scores on an examination in psychology are approximately normally distributed with mean 500 and an unknown standard deviation. The following is a random sample of scores from this examination. 423, 454, 460, 516, 549, 576 Send data to calculator Send data to Excel Find a 90% 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 of formulas.) Lower limit: X S ? Upper limit