the true mean of all scores.

6. The standard deviation of test scores on a certain achievement test is 11.5. A random sample of 90 scores on this test had a mean of 75.3. Based on this sample, find a 90% confidence interval for the true mean of all scores. Then give its lower limit and upper limit.Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.)Lower limit:Upper limit: