Toby's Trucking Company determined that on an annual basis, the distance traveled per truck is normally distributed with a mean of 50.0 thousand miles and a standard deviation of 12.0 thousand miles.

a. What proportion of trucks can be expected to travel between 34.0 and 50.0 thousand miles in the year?
b. What is the probability that a randomly selected truck travels between 34.0 and 38.0 thousand miles in the year?
c. What percentage of trucks can be expected to travel either below 30.0 or above 60.0 thousand miles in the year?
d. How many of the 1,000 trucks in the fleet are expected to travel between 30.0 and 60.0 thousand miles in the year?
e. How many miles will be traveled by at least 80% of the trucks?
f. What will your answers to be (a)-(e) if the standard deviation is 10.0 thousand miles?