In finance the notion of expected value is used to analyze investments for which the investor has an estimate of the chances associated with various returns (and losses). For example, suppose you have the following information about one of your investments: With a probability of 0.7, the investment will return 60 cents for every dollar you invest, and with a probability of 0.3, the investment will lose 20 cents for every dollar you invest. The expected rate of return for this investment is calculated the way we calculate the expected value of a game: Multiply the probability of each outcome by the amount you earn (or by minus the amount if you lose) and add up these numbers.

Amachine that produces a special type of transistor (a component of computers) has a 2% defective rate. the production is considered a random process where each transistor is independent of the others. (a) what is the probability that the 10th transistor produced is the first with a defect? (b) what is the probability that the machine produces no defective transistors in a batch of 100? (c) on average, how many transistors would you expect to be produced before the first with a defect? what is the standard deviation? (d) another machine that also produces transistors has a 5% defective rate where each transistor is produced independent of the others. on average how many transistors would you expect to be produced with this machine before the first with a defect? what is the standard deviation? (e) based on your answers to parts (c) and (d), how does increasing the probability of an event a↵ect the mean and standard deviation of the wait time until success?