Thread: [SOLVED] Pre-Calc applications of equations

Hi, I need help on this word problem:

You have already invested 550$ in a stock with an annual return of 11%. How much of an additional 1100 should be invested at 12% and how much at 6% so that the total return on the entire 1650$ is 9%

I tried to set up my equations as (550 times .11) + (.12x times 1100) + (.06y times 1100) = (1650 times .09)
and x + y = 1100

I am wondering if i am going in the right direction. The answer in the book says 366.67 at 12% and 733.33 at 6% but i tried to work my math and i got nowhere close to that answer.

can anyone help please?

Hello, soccer49!

You're on the right track, but you put "too much" in your equations.

You have already invested $550 in a stock with an annual return of 11%.
How much of an additional $1100 should be invested at 12% and how much at 6%
so that the total return on the entire $1650$ is 9% ?

Let = amounted invested at 12%.
Let = amount invested at 6%.

Then: . .[1]



$550 at 11% returns $60.50 in interest.

dollars at 12% returns dollars in interest.

dollars at 6% returns dollars in interest.

The total interest is: .
. . and we want this to be equal to 9% of $1650 = $148.50

There is our equation: .

Multiply by 100: . .[2]


Solve the system of equation.



And we get: .

Substitute into [1]: .

Thank you very much, yes that would make sense, i am just not very good at setting up the equations.