In one area, the distribution of monthly miles driven by motorists has a mean of 1200 miles and standard deviation of 150 miles. Assume that the number of miles is closely approximated by a normal curve, and find the percent of all motorists driving the following distances.

a) Between 1200 and 1600 miles per month.

b) Greater than 1800 miles per month.

c) Less than 1000 miles per month.

d) 30% of drivers drive more than how many miles per month?