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Altred is saving up money for a down payment on a house. He currently has $4739, but knows he can get a loan at a lower interest rate if he can put down $5336. If heinvests the $4739 in an account that earns 5.1 % annually, compounded monthly, how long will it take Alfred to accumulate the $5336? Round your answer to two decimal places, if necessary.

User DMI
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1 Answer

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Given the word problem, we can deduce the following information:

Principal amount = $4739

Future amount = $5336

Interest = 5.1 % =0.051

To determine the time to accumulate the $5336, we use the compound interest formula:


A=P(1+(r)/(n))^(nt)

A=Future amount=$5336

P=Present amount=$4739

r=interest rate = 0.051

n=number of compounding periods =12

t=time in years

We also note that the number of compounding periods must be 12 since the investment is compounded monthly.

We plug in what we know:


\begin{gathered} A=P(1+(r)/(n))^(nt) \\ 5336=4739(1+(0.051)/(12))^(12t) \\ Simplify\text{ and rearrange} \\ 5336=4739((12.051)/(12))^(12t) \\ 12t=(\ln(5336)/(4739))/(\ln(12.051)/(12)) \\ t=\frac{\operatorname{\ln}(5,336)/(4,739)}{12\operatorname{\ln}(12.051)/(12)} \\ Calculate \\ t=2.33 \end{gathered}

Therefore, the answer is 2.33 years.

User Biffen
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