document.write( "Question 141900: If a sum of 12000 doubles in 5 years at compound interest basis.Then what will be the amount after 20 years, if compounded annually? \n" ); document.write( "

Algebra.Com's Answer #103380 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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If a sum of 12000 doubles in 5 years at compound interest basis.
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\n" ); document.write( "Find the interest rate of this amt doubling in 5 yrs, compounded annually
\n" ); document.write( "12000*(1+r)^5 = 24000
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\n" ); document.write( "(1+r)^5 = $\"24000%2F12000\"$ ; divided both sides by 12000
\n" ); document.write( "(1+r)^5 = 2
\n" ); document.write( "Use the log equiv of exponents:
\n" ); document.write( "5*log(1+r) = log(2)
\n" ); document.write( "log(1+r) = $\".301%2F5\"$
\n" ); document.write( "log(1+r) = .0602
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\n" ); document.write( "Find 10^x of both sides:
\n" ); document.write( "1+r = 1.1487
\n" ); document.write( "r = 1.1487 - 1
\n" ); document.write( "r = .1487 or 14.87% interest to double your money in 5 years
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\n" ); document.write( "Then what will be the amount after 20 years, if compounded annually?
\n" ); document.write( "A = 12000(1.1487)^20
\n" ); document.write( "A = $192,005.50 in 20 years at this interest. \n" ); document.write( "

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