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Solve the following problems. 1. What is the least number of complete years in which a sum of money put out at 20% compound interest will be more than doubled? 2. Herbert invests P20,000 at the beginning of every year in a bank and earns 10% annual interest, compounded at the end of the year. What will be his balance in the bank at the end of three years? 3. What is the difference between the compound interests on P5000 for one and half years at 4% per annum compounded yearly and half-yearly