SOLUTION: How long does it take for an amount of money P to double itself if it's invested at 7% interest compounded 4 times a year? Round your answer to 2 decimal places.

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Question 1161309: How long does it take for an amount of money P to double itself if it's invested at 7% interest compounded 4 times a year? Round your answer to 2 decimal places.
Found 3 solutions by josgarithmetic, MathTherapy, ikleyn:
Answer by josgarithmetic(39620)   (Show Source): You can put this solution on YOUR website!
Each compounding period is percent rate.
 PERIODS          BALANCE
 0                  1
 1                  1.0175
 2                  1.035
 .
 .
 .



Must be full 40 compounding periods, or 3 years and 4 months.
or



, x number of compound periods




Need the WHOLE number of periods.
-------------------------------

Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

How long does it take for an amount of money P to double itself if it's invested at 7% interest compounded 4 times a year? Round your answer to 2 decimal places.
3 years 4 months from the other person is WRONG!. 
You might be able to figure out the correct time, in years! TRY it!!
Answer by ikleyn(52799)   (Show Source): You can put this solution on YOUR website!
.

The basic (starting) equation is

    2 = 

where n is the number of compound periods (quarters).



Take the logarithm base 10 of both sides

    log(2) = 

    n =  = 39.95 = 40 quartes (rounded).


40 quarters = 10 years.


ANSWER.  10 years.

Solved.

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To see many other similar solved problems, look into the lesson
    - Problems on discretely compounded accounts
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Logarithms".


Save the link to this online textbook together with its description

Free of charge online textbook in ALGEBRA-I
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to your archive and use it when it is needed.



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