Miguel has started training for a race. The first time he trains, he runs 0. 5 mile. Each subsequent time he trains, he runs 0. 2 mile farther than he did the previous time.
a) What is the arithmetic series that represents the total distance Miguel has run after he has trained n times?
b) A marathon is 26. 2 miles. What is the least number of times Miguel must run for his total distance run during training to exceed the distance of a marathon?