Please help me I don't understand this! Its been 3 years since Ive done any sats!

11. In determining automobile mileage ratings, it was found that the mpg in the city for a certain model is normally distributed, with a mean of 30 mpg and a standard deviation of 1.7 mpg. Suppose that the car manufacturer samples five cars from its assembly line and tests them for mileage ratings.
a. What is the distribution of the mean mpg for the sample?
b. What is the probability that the mean mpg of the sample will be greater than 31 mpg?
c. What is the probability that the mean mpg of the sample will be less than 29.5 mpg?
Automobile Mileage
Mean	30.00	mpg
S.D.	1.70	mpg
Sample Size	5
Sample Mean	30.00	mpg
a) Sample S.D.		mpg
b) P(Sample Mean > 31 )
c) P(Sample Mean < 29.5 )