Question

I need help with this to see if it is right

Answer 1

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 }(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 }(4.5)/(100)\text{ x t} \\ 112.5=22.5t \\ t=(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 }(8)/(100)\text{ x 2} \\ 108=0.16p \\ p=(108)/(0.16) \\ p=\text{ \$675} \\ Principal=\text{ \$675} \\ New\text{ balance= \$675 + 108 = \$783} \end{gathered}`