To finance a vacation in 2 years, Elsie saves $360 at the beginning of every six months in an account paying interest at 10% compounded semi-annually. (a) What willI be the balance in her account when she takes the vacation? (b) How much of the balance will be interest? (c) If she waits an additional year to start her vacation, and continues to save the same amount of money, how much more money does she have to spend?