An annuity is a regular payment of income made at the end of

英文数学题,关于future value of an annuity: sinking funds
A couple decides on the following plan for their child's college education: When the child is 6 months old, and
every 6 months thereafter, they will deposit $310 into a savings account paying 9.5% interest compounded
semi-annually. After the child's tenth birthday (20 payments), they will stop making payments and let the
money earn interest, at the same rate (8 more years) until the child is 18 and ready for college. How much
money ( to the nearest dollar) will be in the account when the child is ready for college?

英语翻译
You'll find that the future value annuity facor for 6 years and 10 percent is 7.716.
重点想问,这其中的10 percent

关于美国大一金融的数学题目
A man establishes an annuity for retirement by depositing $50,000 into an account that pays 7.2% compounded monthly. Equal monthly withdrawals will be made each month for 5 year, at which time the account will have a zero balance. Each year taxes must be made paid on the interest earned by the account during that year. Find the amount of the monthly withdrawals and how much interest was earned during the first year.