Statistics from Cornell's Northeast Regional Climate Center indicate that Ithaca, NY gets an average of 35.4 inches of rain each year, with a...

Statistics from Cornell's Northeast Regional Climate Center indicate that Ithaca, NY gets an average of 35.4 inches of rain each year, with a standard deviation of 4.2 inches. 

a) During what percentage of years does Ithaca get more than 42 inches of rain? 

(i have calculated this to be 5.8% - I hope this is right!) I am stuck on the following: 

b) Less than how much rain falls in the driest 30% of all years? 

70 in, 33.19 in, 64.60 in, 31.9 in, or 30 in? 

c) A university students is in Ithaca for 8 years. let Y-bar represent the mean amount of rain for those 8 years. 

The sampling distribution model of this mean, y-bar, is best described as? 

and finally: 

d) What's the probability that those 8 years avg less than 30 inches of rain? 

THANK YOU