Question

How much does she have invested in total and in each

Answer 1

Let x be her total investment. Then:

Rate 1: 6% = 0.06

Rate 2: 12% = 0.12

Total interest = $720

`0.06(0.5x)+0.12(0.5x)=720`

Simplify:

`\begin{gathered} 0.03x+0.06x=720 \\ 0.09x=720 \end{gathered}`

Solve for x:

`\begin{gathered} (0.09x)/(0.09)=(720)/(0.09) \\ x=8000 \end{gathered}`

Next, the investment in each be is:

`\begin{gathered} First:\text{ 0.06\lparen0.5\rparen\lparen8000\rparen=240} \\ Second:0.12(0.5)(8000)=480 \end{gathered}`

Answer:

Investment for each: $240 and $480 for the other half

Total investment: $8000