I am studying the Gaussian distribution and am doing one of the problems for practice. The problem states that the standard deviation is equal to 15 and the actual value recorded in the experiment is 385.0. It then asks what is the probability that a single measurement lies in the range of the following.. a.) 385.0-385.1 b.) 400.0-400.1 c.) 451.0-415.1 d.) 370.0-400.0 e.) 355.0-415.0 f.) 340.0-430.0 The following equations are to be used, based on the Gaussian distribution. [PLAIN]http://img62.imageshack.us/img62/8594/what2c.gif [Broken] I couldn't get the same answer as the book. This is the books work for a.) [PLAIN]http://img585.imageshack.us/img585/1271/whati.gif [Broken] There is no explaination as to where 0.399 came from, and the section on Gaussian distribution is very short (As this isn't a statistics course). It says for problems d e and f use the integral equation. Why can't I use the integral equation for all of them? Can anyone help?