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8. A student lends his friend $50 for 1 month. At the end of the month he asks for repayment of the $50 plus purchase of a chocolate bar worth$2.50. What simple interest rate is implied? 9. Determine the effective rate of interest is that is quivalent to the following rates of simple interest. a) i = 2% b) i = 7% 10. You are given that $1,500 accumulates to $1,600 over two years at a rate of simple interest of i. Determine the effective rate of interest in year 2, 12. 11. How much money will be required on dec 31, 2012 to rapay a loan of $2,000 made dec 31, 2009, if i = 7%? 12. In 1492, Queen Isabella sponsored Christopher Columbus journey by giving him $10,000. If i = 3%, how much money would be in the account in 2010? If the bank account earned a simple interest rate of 3%, how much money would be in the account in 2010