4. At what interest rate $7,500 a year ago is equivalent to $1,000 one year from now? 5. If we deposited $3,000 now and an equal amount at the end of each 4 years with i=15% per annum. a. Find the value accumulated after 10 years. b. Calculate the equivalent uniform annual deposits. 6. A land is purchased for $500,000 to be repaid through 10 annual payments with 12% annual interest rate. After making the first 6 payments, the interest rate was reduced to 10% per year .Calculate: a. The reduction in the remaining 4 payments. b. The equivalent constant interest rate