A study was conducted to find average intra-ocular pressure. IOP was measured in 400 people and the mean was found to be 25 mm Hg with a standard detion of 10 mm Hg. What is the range in which 10P of 95% of the population would be lying?
(A) 22-28 mm Hg (B) 20-30 mm Hg (C) 24-26 mm Hg (D) 23-27 mm Hg
(C) Ans: C. 24-26 mm HgStandard error, SE = {standard detion / n)}n = sample sizeC= Confidence coefficient = 1.96 for 95% confidence interval = 2.58 for 99% confidence interval= 3.29 for 99.9% confidence intervalHence in this question, n = 400SD = 10SE = 10/400 = 10/20 = 0.5Mean statistic = 25 mm Hg.Now for 95% confidence interval,C = 2 approximately 95%CI = 25 - 2x0.5 to 25 + 2x0.5 = 24-26 mm HgHence, 95% CI of IOP = 24 to 26 mm Hg.