This document discusses key concepts in capital market theory and risk/return analysis. It defines average and expected rates of return, and how to measure risk through variance and standard deviation. Higher risk investments require a risk premium to attract investors. While risk-averse investors prefer lower risk investments with equal returns, risk-neutral investors only consider returns, and risk-seeking investors prefer higher risk. Returns are often assumed to follow a normal distribution, where standard deviation determines the spread. The probability of returns can then be estimated using the normal distribution.