Mean + 1.96 SD include following % of values in a distribution: September 2012: (A) 68%, (B) 99.50%, (C) 88.70%, (D) 95%
Answer is D. Ans: D i.e. 95% 96 is the approximate value of the 97.5 percentile point of the normal distribution used in probability and statistics. 95% of the area under a normal curve lies within roughly 1.96 standard detions of the mean, and due to the central limit theorem, this number is therefore used in the construction of approximate 95% confidence intervals.