The average starting salary for this year's graduates at a large university (LU) is $20,000 with a standard deviation of $8,000. Furthermore, it is known that the starting salaries are normally distributed.
a. What is the probability that a randomly selected LU graduate will have a starting salary of at least $30,900?
b. Individuals with starting salaries of less than $15,800 receive a low income tax break. What percentage of the graduates will receive the tax break?