document.write( "Question 1140029: At what rate do you need to invest money into a bank account earning continuously compounded interest if you want to double your money in 62 months? \n" ); document.write( "
Algebra.Com's Answer #760481 by Theo(13342)![]() ![]() You can put this solution on YOUR website! continuous compounding formula is f = p * e ^ (r * t)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you want to double your money, then left f = 2 and p = 1.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "formula becomes 2 = 1 * e ^ (r * t)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this is the same as 2 = e ^ (r * t)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "if you want to do it in 62 months, then the formula becomes 2 = e ^ (r * 62).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "take the natural log of both sides of this equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "ln(2) = ln(e ^ (r * 62)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since ln(e ^ (r * 62) is equal to r * 62 * ln(e) and since ln(e) is equal to 1, your formula becomes:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "ln(2) = r * 62\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "divide both sides of this formula by 62 to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "ln(2) / 62 = r\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for r to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "r = .0111797932\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "replace r in the original equation to get:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "2 = e ^ (.0111797932 * 62)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this becomes 2 = 2, confirming the solution is correct.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "your interest rate is .0111797932 * 12 = .1341575188 per year.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's approximately 13.42% per year.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |