Mark is an accountant who has been contributing to his retirement account for the last 15 years with pre-tax dollars. The account com- pounds interest semi-annually at a rate of 5%. He contributes X dollars after each 6-month period, and this has not changed over the life of the account.
a. How much will he have in the account after 20 years of saving? Round numbers to the nearest hundredth.
b. After 20 years of contributions, he needed to withdraw 20% of the money in his account to pay for his children's education. Write an expression for the withdrawal amount.
c. Mark pays T percent of his income in taxes. Write an algebraic expression for the combined total of his tax and the 10% early withdrawal penalty.