Statistics released by the National Highway Safety Administration show that on an average weekend night in urban areas 1 out of every 10 drivers is operating under the influence of alcohol. If 400 drivers are randomly checked on a saturday night, use the normal approximation to the binomial to determine the probability that the number of drunk drivers will be:
a) less than 32
b) more than 49
c) more than 35, but less than 47.