The dean has observed for several years and found that the probability distribution of the salary of the alumni's first job after graduation is normal, with a mean of $60k per year and a standard deviation of $4k.

 

(a)  What's the probability that the alumni get a salary of $64k or more in their first jobs? 

(b) What's the chance that the alumni get a salary between $52k and $68k?

(c)  What is the salary range that 99.7% of the alumni should be belonged to?