The average monthly gasoline purchase for a family with 2 cars is 90 gallons. This statistic has a normal distribution with a standard deviation of 10 gallons. A family is chosen at random.
(a) Find the probability that the family's monthly gasoline purchases will be between 84 and 105 gallons.
(b) Find the probability that the family's monthly gasoline purchases will be less than 95 gallons.
(c) Find the probability that the family's monthly gasoline purchases will be more than 92 gallons.