document.write( "Question 82927: I just want to know if someone could check this and see if it is right and help me on the rest. Not from a textbook. Thank you\r
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\n" ); document.write( "\n" ); document.write( "3) The formula for calculating the amount of money returned for an initial deposit money into a bank account or CD (Certificate of Deposit) is given by
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\n" ); document.write( "A is the amount of returned.
\n" ); document.write( "P is the principal amount initially deposited.
\n" ); document.write( "r is the annual interest rate (expressed as a decimal).
\n" ); document.write( "n is the compound period.
\n" ); document.write( "t is the number of years.\r
\n" ); document.write( "\n" ); document.write( "Carry all calculations to 6 decimals on all assignments then round the answer to the nearest cent.\r
\n" ); document.write( "\n" ); document.write( "Suppose you deposit $10,000 for 2 years at a rate of 10%.\r
\n" ); document.write( "\n" ); document.write( "a) Calculate the return (A) if the bank compounds annually (n = 1). Round your answer to the hundredth's place.\r
\n" ); document.write( "\n" ); document.write( "Answer: $2,200 is the return\r
\n" ); document.write( "\n" ); document.write( "Show work in this space. Use ^ to indicate the power. A= 10,000(1 + .10/1)^1 * 2\r
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\n" ); document.write( "\n" ); document.write( "b) Calculate the return (A) if the bank compounds quarterly (n = 4). Round your answer to the hundredth's place.
\n" ); document.write( "Answer: $8,200\r
\n" ); document.write( "\n" ); document.write( "Show work in this space A = 10,000.00(1 +.10/4)^4*2\r
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\n" ); document.write( "\n" ); document.write( "c) Calculate the return (A) if the bank compounds monthly (n = 12). Round your answer to the hundredth's place.\r
\n" ); document.write( "\n" ); document.write( "Answer: $2,419.20\r
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\n" ); document.write( "10,000.00(1+.10/12)^12*2\r
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\n" ); document.write( "\n" ); document.write( "d) Calculate the return (A) if the bank compounds daily (n = 365). Round your answer to the hundredth's place.\r
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\n" ); document.write( "\n" ); document.write( "e) What observation can you make about the size of the increase in your return as your compounding increases more frequently?
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\n" ); document.write( "\n" ); document.write( "f) If a bank compounds continuously, then the formula takes a simpler, that is
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\n" ); document.write( "where e is a constant and equals approximately 2.7183.
\n" ); document.write( "Calculate A with continuous compounding. Round your answer to the hundredth's place.\r
\n" ); document.write( "\n" ); document.write( "Answer: \r
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\n" ); document.write( "\n" ); document.write( "g) Now suppose, instead of knowing t, we know that the bank returned to us $15,000 with the bank compounding continuously. Using natural logarithms, find how long we left the money in the bank (find t). Round your answer to the hundredth's place.\r
\n" ); document.write( "\n" ); document.write( "Answer: \r
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\n" ); document.write( "\n" ); document.write( "h) A commonly asked question is, “How long will it take to double my money?” At 10% interest rate and continuous compounding, what is the answer? Round your answer to the hundredth's place.\r
\n" ); document.write( "\n" ); document.write( "Answer: \r
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Algebra.Com's Answer #60238 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"A=p%281%2Br%2Fn%29%5E%28n%2At%29\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"A=10000%281%2B0.1%2Fn%29%5E%28n%2A2%29\" Plug in p=10000, r=0.1\r
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\n" ); document.write( "\n" ); document.write( "a) \r
\n" ); document.write( "\n" ); document.write( "Lets calculate the return if the bank compounds annually\r
\n" ); document.write( "\n" ); document.write( "Let n=1 and plug it into \"A=10000%281%2B0.1%2Fn%29%5E%28n%2A2%29\"\r
\n" ); document.write( "\n" ); document.write( "\"A=10000%281%2B0.1%2F1%29%5E%281%2A2%29\" Start with the given expression
\n" ); document.write( "\"A=10000%281%2B0.1%29%5E%281%2A2%29\" Divide 0.1 by 1 to get 0.1
\n" ); document.write( "\"A=10000%281%2B0.1%29%5E%282%29\" Multiply the exponents 1 and 2 to get 2
\n" ); document.write( "\"A=10000%281.1%29%5E%282%29\" Add 1 and 0.1 to get 1.1
\n" ); document.write( "\"A=10000%281.21%29\" Raise 1.1 to 2 to get 1.21
\n" ); document.write( "\"A=12100\" Multiply 10000 and 1.21 to get 12100\r
\n" ); document.write( "\n" ); document.write( "So our return is $12100
\n" ); document.write( "b) \r
\n" ); document.write( "\n" ); document.write( "Lets calculate the return if the bank compounds quarterly\r
\n" ); document.write( "\n" ); document.write( "Let n=4 and plug it into \"A=10000%281%2B0.1%2Fn%29%5E%28n%2A2%29\"\r
\n" ); document.write( "\n" ); document.write( "\"A=10000%281%2B0.1%2F4%29%5E%284%2A2%29\" Start with the given expression
\n" ); document.write( "\"A=10000%281%2B0.025%29%5E%284%2A2%29\" Divide 0.1 by 4 to get 0.025
\n" ); document.write( "\"A=10000%281%2B0.025%29%5E%288%29\" Multiply the exponents 4 and 2 to get 8
\n" ); document.write( "\"A=10000%281.025%29%5E%288%29\" Add 1 and 0.025 to get 1.025
\n" ); document.write( "\"A=10000%281.21840289750992%29\" Raise 1.025 to 8 to get 1.21840289750992
\n" ); document.write( "\"A=12184.0289750992\" Multiply 10000 and 1.21840289750992 to get 12184.0289750992\r
\n" ); document.write( "\n" ); document.write( "So our return is $12184.03
\n" ); document.write( "c) \r
\n" ); document.write( "\n" ); document.write( "Lets calculate the return if the bank compounds monthly\r
\n" ); document.write( "\n" ); document.write( "Let n=12 and plug it into \"A=10000%281%2B0.1%2Fn%29%5E%28n%2A2%29\"\r
\n" ); document.write( "\n" ); document.write( "\"A=10000%281%2B0.1%2F12%29%5E%2812%2A2%29\" Start with the given expression
\n" ); document.write( "\"A=10000%281%2B0.00833333333333333%29%5E%2812%2A2%29\" Divide 0.1 by 12 to get 0.00833333333333333
\n" ); document.write( "\"A=10000%281%2B0.00833333333333333%29%5E%2824%29\" Multiply the exponents 12 and 2 to get 24
\n" ); document.write( "\"A=10000%281.00833333333333%29%5E%2824%29\" Add 1 and 0.00833333333333333 to get 1.00833333333333
\n" ); document.write( "\"A=10000%281.22039096137556%29\" Raise 1.00833333333333 to 24 to get 1.22039096137556
\n" ); document.write( "\"A=12203.9096137556\" Multiply 10000 and 1.22039096137556 to get 12203.9096137556\r
\n" ); document.write( "\n" ); document.write( "So our return is $12203.91
\n" ); document.write( "d) \r
\n" ); document.write( "\n" ); document.write( "Lets calculate the return if the bank compounds daily\r
\n" ); document.write( "\n" ); document.write( "Let n=365 and plug it into \"A=10000%281%2B0.1%2Fn%29%5E%28n%2A2%29\"\r
\n" ); document.write( "\n" ); document.write( "\"A=10000%281%2B0.1%2F365%29%5E%28365%2A2%29\" Start with the given expression
\n" ); document.write( "\"A=10000%281%2B0.000273972602739726%29%5E%28365%2A2%29\" Divide 0.1 by 365 to get 0.000273972602739726
\n" ); document.write( "\"A=10000%281%2B0.000273972602739726%29%5E%28730%29\" Multiply the exponents 365 and 2 to get 730
\n" ); document.write( "\"A=10000%281.00027397260274%29%5E%28730%29\" Add 1 and 0.000273972602739726 to get 1.00027397260274
\n" ); document.write( "\"A=10000%281.22136930163979%29\" Raise 1.00027397260274 to 730 to get 1.22136930163979
\n" ); document.write( "\"A=12213.6930163979\" Multiply 10000 and 1.22136930163979 to get 12213.6930163979\r
\n" ); document.write( "\n" ); document.write( "So our return is $12213.69\r
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\n" ); document.write( "\n" ); document.write( "e) What observation can you make about the size of the increase in your return as your compounding increases more frequently?\r
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\n" ); document.write( "\n" ); document.write( "As the compounding frequency increases, the return slowly approaches some finite number (which in this case appears to be about $12213.69). Think about it, banks wouldn't be too fond of shelling out an infinite amount of cash.\r
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\n" ); document.write( "\n" ); document.write( "f)Calculate A with continuous compounding\r
\n" ); document.write( "\n" ); document.write( "Using the contiuous compounding formula \"A=Pe%5E%28rt%29\" where e is the constant 2.7183 and letting r=0.1, P=10,000, and t=2 we get\r
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\n" ); document.write( "\n" ); document.write( "\"A=10000%282.7183%29%5E%280.1%2A2%29\" Start with the given equation\r
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\n" ); document.write( "\n" ); document.write( "\"A=10000%282.7183%29%5E%280.2%29\" Multiply 0.1 and 2\r
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\n" ); document.write( "\n" ); document.write( "\"A=10000%281.22140439115573%29\" Raise 2.7183 to 0.2\r
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\n" ); document.write( "\n" ); document.write( "\"A=12214.0439115572\" Multiply\r
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\n" ); document.write( "\n" ); document.write( "So using continuous compounding interest we get a return of $12,214.04 (which is real close to what we got from a daily compounding frequency)\r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "g)Now suppose, instead of knowing t, we know that the bank returned to us $15,000 with the bank compounding continuously. Using natural logarithms, find how long we left the money in the bank (find t)\r
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\n" ); document.write( "\n" ); document.write( "\"15000=10000e%5E%280.1t%29\" \r
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\n" ); document.write( "\n" ); document.write( "\"15000%2F10000=e%5E%280.1t%29\" Divide both sides by 10,000\r
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\n" ); document.write( "\n" ); document.write( "\"1.5=e%5E%280.1t%29\" \r
\n" ); document.write( "\n" ); document.write( "\"ln%281.5%29=0.1t\" Take the natural log of both sides. This eliminates \"e\".The natural log (pronounced \"el\" \"n\") is denoted \"ln\" on calculators.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"ln%281.5%29%2F0.1=t\" Divide both sides by 0.1\r
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\n" ); document.write( "\n" ); document.write( "So we get\r
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\n" ); document.write( "\n" ); document.write( "\"t=0.4054%2F0.1=4.054\"\r
\n" ); document.write( "\n" ); document.write( "\"t=4.054\"\r
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\n" ); document.write( "\n" ); document.write( "So it will take about 4 years to generate $15,000\r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "h) A commonly asked question is, “How long will it take to double my money?” At 10% interest rate and continuous compounding, what is the answer?\r
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\n" ); document.write( "\n" ); document.write( "Since we want to double our money, let A=2*10,000. So A=20,000. Now solve for t:\r
\n" ); document.write( "\n" ); document.write( "\"20000=10000e%5E%280.1t%29\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"20000%2F10000=e%5E%280.1t%29\" Divide both sides by 10,000\r
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\n" ); document.write( "\n" ); document.write( "\"2=e%5E%280.1t%29\" \r
\n" ); document.write( "\n" ); document.write( "\"ln%282%29=0.1t\" Take the natural log of both sides. This eliminates \"e\".The natural log (pronounced \"el\" \"n\") is denoted \"ln\" on calculators.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"ln%282%29%2F0.1=t\" Divide both sides by 0.1\r
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\n" ); document.write( "\n" ); document.write( "So we get\r
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\n" ); document.write( "\n" ); document.write( "\"t=0.69314%2F0.1=6.9314\"\r
\n" ); document.write( "\n" ); document.write( "\"t=6.9314\"\r
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\n" ); document.write( "\n" ); document.write( "So it will take about 7 years to double your money.
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