Sarah contributes $280 at the end of every month to a savings account that earns interest at a rate of 3.4% compounded semi-annually. After 12 years of making deposits, she stops making payments and leaves the money to grow for another 3 years. 1. How much money does Sarah have in the account at the end of the 15-year period? 2. How much interest did Sarah earn over the 15 -year period