This chapter discusses decision making under risk and uncertainty in managerial economics. It covers the importance of understanding the application of risk and probability distribution in investment evaluation, evaluating investments in a risk environment, and making investment decisions in uncertainty. The text highlights that most economic decisions are made with imperfect information due to various factors such as macroeconomic conditions, consumer tastes, competitors' reactions, and societal constraints. Effective decision-making is essential for successful managerial performance.