Question

I need help with this to see if it is right

Answer 1

Solution:

The interest is taken to be simple interest

$\begin{gathered} Simple\text{ interest = p x r x t} \\ Where\text{ p = principal} \\ r=rate\text{ \lparen\%\rparen} \\ t=time\left(years\right) \\ \end{gathered}$

Amount (New Balance) = Principal + Interest.

For row 1

$\begin{gathered} p=\text{ \ }300,\text{ r=3\%, t=4} \\ Interest=300\text{ x }\frac{3}{100}\text{ x4= \ 36} \\ \\ New\text{ Balance = \ 36 + \ 300 = \ 336} \end{gathered}$

For row 2:

$\begin{gathered} p=\text{ \ 450, r=?, t= 3, I = 67.5} \\ 67.5=450\text{ x r x 3} \\ r=\frac{67.5}{450\text{ x 3}} \\ r=0.05 \\ =0.05\text{ x 100 = 5\%} \\ Rate=5\text{ \%} \\ \\ New\text{ balance = \ 450 + \ 67.5=\ 517.50} \end{gathered}$

For row 3

$\begin{gathered} p=\text{ \ 500, r=4.5\%, t=?, I=\ 112.5} \\ 112.5=500\text{ x }\frac{4.5}{100}\text{ x t} \\ 112.5=22.5t \\ t=\frac{112.5}{22.5} \\ t=5\text{ years} \\ Time\text{ = 5years} \\ \\ New\text{ balnace= \ 500 +\ 112.5 = \ 612.5} \end{gathered}$

For Row 4:

$\begin{gathered} r=8\text{ \%, t = 2, I = \ 108, p=?} \\ 108=p\text{ x }\frac{8}{100}\text{ x 2} \\ 108=0.16p \\ p=\frac{108}{0.16} \\ p=\text{ \ 675} \\ Principal=\text{ \ 675} \\ New\text{ balance= \ 675 + 108 = \ 783} \end{gathered}$