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A financial adviser was showing a client the value, [#permalink]
Could anyone help me understand why can we infer it is a compound interest?
Thank you!­

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Re: A financial adviser was showing a client the value, [#permalink]
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apoorvmht wrote:
A financial adviser was showing a client the value, rounded to the nearest cent, of an initial investment of $100.00 after 5, 10, 15, 20, 25, and 30 years, under the assumption that the value increases by r% per year for some positive constant r. The adviser correctly gave $130.01 for the value after 5 years. However, the adviser inadvertently made two transcription errors, and as a result, two of the remaining values shown to the client were incorrect.

Assuming the options provided are the remaining five amounts shown to the client, select for First error the lesser of the two incorrectly transcribed values and select for Second error the greater of the two incorrectly transcribed values. Make only two selections, one in each column.

 

We know that \(A = P(1 + r)^n\)

\(130.01 = 100 * (1+r)^5\)
\((1 + r)^5 = 1.3001\)

Now you can simply keep multiplying every previous value with 1.3001 on the calculator.

So Amount after 10 years =\( 130.01 * (1 + r)^{5} = 130.01 * 1.3001 = 169.03\)
This amount is shown as 160.02 so ERROR of $9. 
ANSWER


Amount after 15 years = 169.03 * 1.3001 = 219.75


Amount after 20 years = 219.75 * 1.3001 = 285.70


Amount after 25 years = 285.70 * 1.3001 = 371.43
This amount is shown as 317.43 so ERROR of a bigger amount. Select as Second Error. So select previous error as First Error.
ANSWER

Amount after 30 years = 371.43 * 1.3001 = 482.90


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A financial adviser was showing a client the value, [#permalink]
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mehul2494
ruis
Hi, even if one does not realize initially, the values should be 100, 130.01 and then 160.02 and 190.03 and then 220.04
But you do not have value except 160.02, so either all else are wrong or 160.02 is wrong.
Thus, you could check if it is simple interest by adding 130.01-100 or 30.01 successively to 100.­
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Re: A financial adviser was showing a client the value, [#permalink]
 
chetan2u wrote:
apoorvmht wrote:
A financial adviser was showing a client the value, rounded to the nearest cent, of an initial investment of $100.00 after 5, 10, 15, 20, 25, and 30 years, under the assumption that the value increases by r% per year for some positive constant r. The adviser correctly gave $130.01 for the value after 5 years. However, the adviser inadvertently made two transcription errors, and as a result, two of the remaining values shown to the client were incorrect.

Assuming the options provided are the remaining five amounts shown to the client, select for First error the lesser of the two incorrectly transcribed values and select for Second error the greater of the two incorrectly transcribed values. Make only two selections, one in each column.
 


So, we are looking at compound interest at r% per year.
Finding r here would be cumbersome, So, let us take rate of interest as R for a time period of 5 years as we are talking of amount after every five years.

So, if time period is 5 years, the R is \(\frac{130.01-100}{100}*100\) or 30.01%
10 years: After another 5 years, amount will become \(130.01*(1+\frac{30.01}{100})=130.01*1.3001~169\neq 160\)
15 years: After another 5 years, amount will become \(169*(1+\frac{30.01}{100})=169*1.3001~219\)
20 years: After another 5 years, amount will become \(219*(1+\frac{30.01}{100})=219*1.3001~285\)
25 years: After another 5 years, amount will become \(285*(1+\frac{30.01}{100})=285*1.3001~371\neq 317\)
30 years: After another 5 years, amount will become \(371*(1+\frac{30.01}{100})=371*1.3001~482\)

The values are 160 and 317

Mathematically
CI formula \(P(1+\frac{r}{100})^t=Amount\)
\(100(1+\frac{r}{100})^5=130.01\)
\((1+\frac{r}{100})^5=1.3001\)
After 10 years: \(100(1+\frac{r}{100})^10\)
\(100((1+\frac{r}{100})^5)^2=130.01*(1+\frac{r}{100})^5=130.01*1.3001\)
And so on
 

­chetan2u apart from noticing the values in the answer choices, the information from the question that helps us understand that we are talking about compound interest is the highlighted one?

thanks in advance
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Re: A financial adviser was showing a client the value, [#permalink]
ruis wrote:
Could anyone help me understand why can we infer it is a compound interest?
Thank you!­

Official answer:

­
with the simple interest, we have many answer pairs. We can easily calculate the interest value and projections for coming years which do not match for many values. This can be a hint for trying compound interest. ig
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Re: A financial adviser was showing a client the value, [#permalink]
rjg_25 wrote:
ruis wrote:
Could anyone help me understand why can we infer it is a compound interest?
Thank you!­

Official answer:

­
with the simple interest, we have many answer pairs. We can easily calculate the interest value and projections for coming years which do not match for many values. This can be a hint for trying compound interest. ig

­of course we can move on to the calculations but it is time consuming, so could we consider the statement under the assumption that the value increases by r% per year for some positive constant r as an evidence for the compound interest?
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Re: A financial adviser was showing a client the value, [#permalink]
 
Gmatguy007 wrote:
rjg_25 wrote:
ruis wrote:
Could anyone help me understand why can we infer it is a compound interest?
Thank you!­

Official answer:

­
with the simple interest, we have many answer pairs. We can easily calculate the interest value and projections for coming years which do not match for many values. This can be a hint for trying compound interest. ig

­of course we can move on to the calculations but it is time consuming, so could we consider the statement under the assumption that the value increases by r% per year for some positive constant r as an evidence for the compound interest?

We can't right, r is always +ve constant. But about the calcuation part; the calcuation is very easy here, after 1st interest we get 130.01 from 100 so simple interest is 30.01, for other years we can simply add 30.01 we get 160.02, 190.03, 220.04, 250.05, 280.06 we can see there are more than 3 choices for 2 errors.
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Re: A financial adviser was showing a client the value, [#permalink]
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