Suppose that the birth weight of newborn babies in the U.S is normally distributed with a mean of 7 pounds and a standard deviation of 1.6 pounds. Let the random variable X be the birth weight of a randomly selected record of live birth.

a) What is the distribution of X?
b) What is the probability that a randomly selected record shows a birth weight less than 5 pounds?
c) What is the probability that a randomly selected record shows a birth weight greater than eleven pounds?
d) What is the probability that a randomly selected record shows a birth weight between 6 and 9 pounds