According to the National Education Association, the mean salary of public school teachers was $35,819 in 1994. Assume that the 1994 salaries of all public school teachers had a bell-shaped distribution with a mean of $35,819 and a standard deviation of $3,500. Using the empirical rule, find the percentage of public teachers whose 1994 salaries were between
a. $28,819 and $42,819
b. $32,319 and $39,319
c. $25,319 and $46,319