Question 740866: At 4.75 percent interest, how long does it take to quadruple your money?
At 4.75 percent interest, how long does it take to double your money?
Found 3 solutions by lynnlo, Alan3354, ikleyn:
Answer by lynnlo(4176)   (Show Source):
Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! At 4.75 percent interest, how long does it take to quadruple your money?
At 4.75 percent interest, how long does it take to double your money?
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You didn't give the compounding period, if any.
Compounded annualy:
2*Amt = Amt*1.0475^t (t in years)
1.0475^t = 2
t*log(1.0475) = log(2)
t = log(2)/log(1.0475)
t =~ 14.936 years to double
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Do the others the same way.
Answer by ikleyn(53427)  (Show Source):
You can put this solution on YOUR website! .
At 4.75 percent interest, how long does it take to quadruple your money?
At 4.75 percent interest, how long does it take to double your money?
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Let M be the original amount deposited in the bank at 4.75% of simple annual interest.
To answer first question, write a standard equation for the future value of simple interest.
Keep in mind that future value in this case is 4M, the quadrupled initial amount.
Your equation is
4M = M*(1+0.0475*t),
where 't' is the time in years.
In the equation, reduce the common factor M in both sides
4 = 1 + 0.0475t,
4-1 = 0.0475t,
3 = 0.0475t,
t = 3/0.0475 = 63.158 years, or 63 years and 58 days, approximately.
It is the answer for the first question.
To answer the second question, make similar calculations.
Keep in mind that future value in this case is 2M, the doubled initial amount.
2M = M*(1+0.0475t),
2 = 1 + 0.0475t
2-1 = 0.0475t
1 = 0.0475t
t = 1/0.0475 = 21.053 years, or 21 years and 19 days, approximately.
It is the answer to your second question.
At this point, the problem is solved completely: all questions are answered and the steps are provided.
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