A manager of a popular retail store knows that the distribution of purchase amounts by its customers is approximately normal with a mean of $28 and a standard deviation of $9. a. What is the probability that a randomly selected customer will spend less than $15? ' 0.125 v' b. What is the probability that a randomly selected customer will spend $20 or more? ' [Select] v' c. What is the probability that a randomly selected customer will spend $28 or more? ' 0.43 v