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If something earns 10% compound interest in a year, how much interest
does it earn in half a year?
(Now if it were *simple interest*, it would be 5%. But I don't how what
it is for compound interest...)
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Invisible wrote:
> If something earns 10% compound interest in a year, how much interest
> does it earn in half a year?
>
> (Now if it were *simple interest*, it would be 5%. But I don't how what
> it is for compound interest...)
GIYF or WIYF:
http://en.wikipedia.org/wiki/Compound_interest
It depends on the frequency of the compounding.
--
~Mike
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On 23-Oct-08 17:58, Invisible wrote:
> If something earns 10% compound interest in a year, how much interest
> does it earn in half a year?
>
> (Now if it were *simple interest*, it would be 5%. But I don't how what
> it is for compound interest...)
Isn't this why logarithms were invented?
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andrel wrote:
> On 23-Oct-08 17:58, Invisible wrote:
>> If something earns 10% compound interest in a year, how much interest
>> does it earn in half a year?
>>
>> (Now if it were *simple interest*, it would be 5%. But I don't how
>> what it is for compound interest...)
>
> Isn't this why logarithms were invented?
Probably. But I don't know how to correctly apply them in this case...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Orchid XP v8 wrote:
> Probably. But I don't know how to correctly apply them in this case...
GIYF. http://www.google.com/search?q=continuous+compound+interest
http://www.moneychimp.com/articles/finworks/continuous_compounding.htm
--
Darren New / San Diego, CA, USA (PST)
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On 23-Oct-08 21:23, Orchid XP v8 wrote:
> andrel wrote:
>> On 23-Oct-08 17:58, Invisible wrote:
>>> If something earns 10% compound interest in a year, how much interest
>>> does it earn in half a year?
>>>
>>> (Now if it were *simple interest*, it would be 5%. But I don't how
>>> what it is for compound interest...)
>>
>> Isn't this why logarithms were invented?
>
> Probably. But I don't know how to correctly apply them in this case...
>
interest is an exponential function. Taking a logarithm makes it linear.
after one year you have 10% interest, so in total 1.1 times your
starting point. After a half year you will have
exp( (log(1.1)-log(1)) / 2) or 1.0488 times as much.
I admit that simply taking the square root of 1.1 would have been
simpler, but this formula also works for 4 months. (Ok, that is
effectively a cubic root. Let's say that it also works for 100 days ;) ).
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Invisible wrote:
> If something earns 10% compound interest in a year, how much interest
> does it earn in half a year?
>
> (Now if it were *simple interest*, it would be 5%. But I don't how what
> it is for compound interest...)
If a 10% AY account is compounded at a sufficient frequency, it will
earn about 4.88% in half of a year.
Regards,
John
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On Thu, 23 Oct 2008 16:58:56 +0100, Invisible <voi### [at] dev null> wrote:
>If something earns 10% compound interest in a year, how much interest
>does it earn in half a year?
>
>(Now if it were *simple interest*, it would be 5%. But I don't how what
>it is for compound interest...)
Excel is your friend too :)
=PV*(1+R)^N
--
Regards
Stephen
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andrel wrote:
> interest is an exponential function. Taking a logarithm makes it linear.
> after one year you have 10% interest, so in total 1.1 times your
> starting point. After a half year you will have
>
> exp( (log(1.1)-log(1)) / 2) or 1.0488 times as much.
>
> I admit that simply taking the square root of 1.1 would have been
> simpler, but this formula also works for 4 months. (Ok, that is
> effectively a cubic root. Let's say that it also works for 100 days ;) ).
Thanks. This is what I was trying to work out.
(I'm not actually interested in compound interest, but rather
exponential damping. I want to figure out how much damping to apply at a
different framerate to still achieve the same degree of damping per
second...)
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