document.write( "Question 716005: I need help in finding quarterly interest. The question is: The bank guarantees to triple your money in 10 years if you open an account this month. The interest rate will be compounded quarterly. What is the quarterly interest rate? \n" ); document.write( "
Algebra.Com's Answer #441551 by lwsshak3(11628)\"\" \"About 
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I need help in finding quarterly interest. The question is: The bank guarantees to triple your money in 10 years if you open an account this month. The interest rate will be compounded quarterly. What is the quarterly interest rate?
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\n" ); document.write( "Formula for compound interest: A=P(1+i)^n, P=initial investment, i=interest per period, n=number of periods, A=amount after n-periods.
\n" ); document.write( "For given problem:
\n" ); document.write( "rewrite formula: A/P=(1+i)^n=3
\n" ); document.write( "n=10*4=40 quarterly periods
\n" ); document.write( "(1+i)^40=3
\n" ); document.write( "take log of both sides
\n" ); document.write( "40log(1+i)=log3
\n" ); document.write( "log(1+i)=log3/40≈.011928
\n" ); document.write( "convert to exponential form:
\n" ); document.write( "(1+i)=10^0.011928≈1.0278
\n" ); document.write( "i=1.0278-1≈.0278≈2.78%
\n" ); document.write( "annual interest rate=4*2.78≈11.12% \n" ); document.write( "
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