4. In a certain area, 20% of oil wells drilled will strike oil. Twenty wells are drilled, far enough apart that they will be independent. a) What is the probability that between 3 and 5 (inclusive) of them strike oil? b) What is the probability that at least 3 strike oil? c) How many of the wells do you expect to strike oil? d) Suppose the total prot (in millions) will be 5X2 20. What is the expected prot from 20 wells drilled? c) How many wells should be drilled if you want to have at least a 90% chance of striking oil