Hey Guys I came across this question in a third party prep provider. I have changed the question around to avoid copyright violations. "The percentage changes in annual earnings for a company are approximately normally distributed with a mean of 5% and a standard deviation of 12%. The probability that the average change in earnings over the next five years will be greater than 15.5% is closest to: a) 10% b) 2.5% c) 5.0% Answer: B The first time I attempted this question I firstly tried to normalise it the ordinary way. 15.5-5/12 However looking at the answers you need to divide the numerator by the standard error. Can somebody explain to me why this is so and how you can differentiate a ordinary normalising question from one such as this? Was the “over the next 5 years” part of the question the give away? Thanks