9. What interest rate, compounded semi-annually is needed for a $500 investment to increase to $634.12 after 6 years? 10. Charles pays $45 for a car stereo and borrows the remaining amount. The loan payments are $25 per month for 1 year. The interest rate is 18.6% /a compounded monthly. What was the selling price of the car stereo? For each question below, provide well-organized solutions showing all required steps. While calculators may be used for numerical calculations, other mathematical steps must be shown and justified in your written solutions and specific marks may be allocated for these steps. Be sure to demonstrate your understanding of the grade 11 course material by justifying your answers using the knowledge and skills learned in our class.