What annual interest rate, compounded semi-annually for 8 years, will be needed for An investment of $15,000, to grow to $45,000? 

Let's assume that you want to buy a house in 7 years and estimate that the prompt payment and Necessary initial expenses will be $40,000 at that time. How much do you need to deposit to the beginning of each year in the next 7 years to accumulate the $40,000 if you can earn 8% annually compound semi-annually on your deposits?