SOLUTION: Please help never understood how to do these problems. Thanks in advance If you put 2000 an interest bearing account is compounded quarterly(4 times a year)at 6%, how long will

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Please help never understood how to do these problems. Thanks in advance If you put 2000 an interest bearing account is compounded quarterly(4 times a year)at 6%, how long will       Log On


   



Question 1035884: Please help never understood how to do these problems. Thanks in advance
If you put 2000 an interest bearing account is compounded quarterly(4 times a year)at 6%, how long will it take for your money to triple?

Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
If you put 2000 an interest bearing account is compounded quarterly(4 times a year)at 6%, how long will it take for your money to triple?
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A(t) = P(1+(r/n))^(n*t)
3*2000 = 2000(1+(0.06/4))^(4*t)
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Solve:
(1+(0.06/4))^(4t) = 3
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4t*log(1.015) = log(3)
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4t = 73.79
time = 18.45 years
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Cheers,
Stan H.
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Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
you just have to plug the right numbers into
the formula. Sometimes you have to do a
conversion to logs base 10 to get answer.
( I can never remember formula -I keep
it handy for problems )
--------------------------------
+A+=+P%2A%28+1+%2B+r%2Fn+%29%5E%28n%2At%29+
+P+=+2000+ original investment
+n+=+4+ compounding 4 times a year
+r+=+.06+ 6% interest rate
--------------------------------
If you want to triple your original investment,
just say +A+=+3P+, or in this case:
+A+=+3%2A2000+
+A+=+6000+
Find +t+, number of years you leave the money in
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+A+=+P%2A%28+1+%2B+r%2Fn+%29%5E%28n%2At%29+
+6000+=+2000%2A%28+1+%2B+.06%2F4+%29%5E%284t%29+
+3+=+%28+1+%2B+.015+%29%5E%284t%29+
+3+=+1.015%5E%284t%29+
Take the log base 10 of both sides
+.47712+=+%284t%29%2A.006466+
+4t+=+73.78857+
+t+=+18.4471+
+.4471%2A12+=+5.36+
It will take 18 years and 6 months
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check:
+3+=+%28+1+%2B+.015+%29%5E%284t%29+
+3+=+%28+1+%2B+.015+%29%5E%284%2A18.4471%29+
+3+=+1.015%5E73.7884+
+3+=+2.99998+
close enough
Hope this helps