Alma invests $300 in an account that compounds interest annually. After 2 years, the balance of the account is $329.49. To the nearest tenth of a percent, what is the rate of interest on the account?

Respuesta :

Invested amount (P) = $300.

Time in years (t) = 2 years.

Balance after 2 years (A) = $329.49.

Let us assume rate of interest = r % compounds annually.

We know, formula for compound interest

[tex]A=P(1+r)^t[/tex]

Plugging values in formula, we get

[tex]329.49=300(1+r)^2[/tex]

[tex]\mathrm{Divide\:both\:sides\:by\:}300[/tex]

[tex]\frac{300\left(1+r\right)^2}{300}=\frac{329.49}{300}[/tex]

[tex]\left(1+r\right)^2=1.0983[/tex]

Taking square root on both sides, we get

[tex]1+r=\sqrt{1.0983}[/tex]

[tex]\mathrm{Subtract\:}1\mathrm{\:from\:both\:sides}[/tex]

[tex]1+r-1=\sqrt{1.0983}-1[/tex]

[tex]r=\sqrt{1.0983}-1[/tex]

[tex]r=1.048-1[/tex]

r=0.048.

Converting it into percentage by multiplying by 100.

r=0.048 × 100

r  = 4.8 %

Therefore, the rate of interest on the account is 4.8% compounds annually.