Let X be the random variableintroductory salaries ($).

a. Calculate Pr(X < 23000) and multiply the answer by 100.

I get approximately 26.38%.

b. Calculate Pr(21250 < X < 23750) and multiply the answer by 100.

I get approximately 24.98%.

Without knowing how you've been taught to calculate such probabilities (using tables, technology such as TI-84 or TI-89 calculators, numerical integration of the pdf etc.) it's impossible to provide further relevant help.

Let X be the random variableannual snowfall (inches).

a. Calculate Pr(X > 111.8)

I get 0.3897 (correct to four decimal places).

Let Y be the random variablenumber of years out of 40 randomly picked years that X > 111.8.

Then Y ~ Binomial(n = 40, p = 0.3897).

You need to calculate Pr(Y = 40) ......

b. Proceed similar to part a. Calculate Pr(105 < X < 112) etc.