Please help!

1. On the day that his first child was born, Ezio Auditore de Firenze deposited $6,200 into an investment account. The only purpose for the account was to pay for his son's first year of college tuition. Assume that his son, Flavia, started college on his 18th birthday and his first-year tuition payment had to be made that day. The amount needed on that day was $45,000. If that was indeed the amount of money in the account on Flavia's 18th birthday, what annual rate of return did Ezio earn on his investment account? 2. Marcus Holloway has $1,000 that he will use as a down payment on a car. Assuming that he can afford a payment of $225 per month, how much can Marcus spend on a car (that is, what is the total cost of the car that Marcus can purchase) if the interest rate is 3.75% and if he will finance his purchase with a 5 year, monthly payment loan? 3. Suppose Crash Bandicoot deposits $5,000 into an account earning 4 percent interest, compounded monthly and Crash also make monthly contributions of $50 (first monthly contribution made one month after the initial deposit is made). How many years (rounded to one decimal place for example, 32.1843 year = 32.2) will it take for the account to grow to $7,500 in this case? 4. Assume that Ratchet and Clank are trying to borrow money from you to finance their new business. Assume that Ratchet and Clank promise to repay you in three installments, one payment of $5,000 to be made exactly 2 years from today, a second payment of $10,000 to be made exactly 5 years from today, and a final payment of $15,000 to be made 8 years from today. If your opportunity cost of funds is 7.5% p.a., (that is, use an interest rate of 7.5% for this question), how much should you be willing to lend Ratchet and Clank today