As parts come off a production line they are stored in trays capable of holding 30 parts each. If the average tray contains 6 defective parts and you sample only 1 part from each tray, what is the probability that the part you selected will be a good one?
If a secretary entered 280 product inquires last month and 20 of them contained errors that led to lost costumers, what is the probability that the secretary will lose the next customer due to error?