Please Help with this Stat Q

Hi Everybody,

I am stuck on these stat questions and I would very much appreciate any help that I get.

The introductory salaries for medical billing clerks are normally distributed with a mean of $24,800 and a standard deviation of $2850.

a. What percent of introductory salaries are less than $23,000?

b. What percent of introductory salaries are between $21,250 and $23,750?

-and-

The amount of annual snowfall in a certain mountain range is normally distributed with a mean of 109 inches, and a standard deviation of 10 inches.

a. What is the probability that the mean annual snowfall during 40 randomly picked years will exceed 111.8 inches?

b. What is the probability that the mean annual snowfall during 40 randomly picked years will be between 105 inches and 112 inches?

Thanks.