A sample of the salaries of assistant professors on the business faculty at a local university revealed

Question:

A sample of the salaries of assistant professors on the business faculty at a local university revealed a mean income of $72,000 with a standard deviation of $3,000.
a. Using Chebyshev’s theorem, what percentage of the faculty earns at least $66,000 but no more than $78,000?
b. Using Chebyshev’s theorem, what percentage of the faculty earns at least $63,000 but no more than $81,000?