# The mean +/- 0.67 standard deviations cuts off 25% in each tail of the Normal distribution. Hence…

The mean +/_ 0.67 standard deviations cuts off 25% in

each tail of the Normal distribution. Hence the middle 50% of the distribution

lies within +/_ 0.67 standard deviations of the mean. Use this fact to

calculate the inter-quartile range for the distribution x ~ N(200, 256).