Question

Ahmad invested his savings in two investment funds. The $4000 that he invested in Fund A returned a 10% profit. The amount that he invested in Fund Breturned a 3% profit. How much did he invest in Fund B, if both funds together returned a 7% profit?

Answer 1

Let x be the amount that Ahmad invested in Fund A, and y be the amount invested in Fund B, if together returned a 7% profit, we can set the following system of equations:

$\begin{gathered} x+y=4000, \\ 0.10x+0.03y=0.07\cdot4000. \end{gathered}$

Solving the first equation for x we get:

$\begin{gathered} x+y-y=4000-y, \\ x=4000-y\text{.} \end{gathered}$

Substituting the above equation in the second one we get:

$0.10(4000-y)+0.03y=0.07\cdot4000.$

Solving for y we get:

$\begin{gathered} 400-0.10y+0.03y=280, \\ -0.07y=-120, \\ y=1714.2857 \\ y\approx1714.29 \end{gathered}$

Answer: $1714.29.