According to records of Commonwealth Edison, the mean electric consumption during January is 1,650 kilowatt hours, with a standard deviation of 320 kilowatt hours. The monthly electric consumption for January follows a normal distribution.
a. Selecting a customer at random, find the probability that the customer uses less than 1,000 kilowatt hours in January.
b. Selecting a customer at random, find the probability that the customer uses between 1,500 and 2,500 kilowatt hours in January.
c. Commonwealth Edison wants to identify its heaviest users, which are those that are in the top 6% of electric consumption. How many kilowatt hours in January would qualify for the heavy user classification?