‘Applications in science, medicine, and operations research’ applies theories of probability to a range of different subject areas. Brownian motion of particles in liquid was explained by Einstein using Gaussian law. Random number sequences generated by computers are not truly random, and are open to bias or fraud. However, Monte–Carlo simulations use the Law of Large Numbers to offset this bias. Errors in computer code itself can be solved by using the concept of majority vote. Bayes' Rule and expected utility can be used to answer complex ethical dilemmas in biomedical science. Companies can also use probability to maximise profits through optimising overbooking systems and queues.