1) A loan of $8,600 is charged interest at 6.70% compounded semi-annually for the first 3.5 years, and then 5.20% compounded monthly thereafter. How much is owed at the end of 8 years?

2) A loan of $17,000 today is to be repaid by 3 equal payments due in 3 years, 7 years, and 12 years respectively from the date of the loan. If interest on the loan is 5.75% p.a. compounded semi-annually, what is the amount of each payment?

3) A debt of $9,500 accumulated interest at 6.00% p.a. compounded quarterly for 15 months, after which the rate changed to 5.20% p.a. compounded semi-annually for the next 6 months until the loan's due date. What total amount was owed on the due date?

4) Payments of $3,500 due 6 months ago and $5,000 due in 8 months from now will be replaced by one equivalent payment six months from now. If money can earn 7% simple interest, what is the size of this payment?