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At a certain gas station, 70% of the customers use regular gas and 30% use premium gas. Of those customers using regular gas, only 80% fill their tanks. Of those using premium gas, only 55% fill their tanks. Let A = { Regular Gas}, B= (Premium Gas}, and F=(Fill) a. What is the probability that the next customer fills tank? (10 pts) b. If the next customer fills the tank, what is the probability premium gas is used? (10 pts)