Tori invested $8000 in money market funds. Part was invested at 5% simple interest and the rest was invested at 7% simple interest. At the end of the year, Tori had earned $496 in interest. How much did she invest in each fund?

Question

Tori invested $8000 in money market funds.  Part was invested at 5% simple interest and the rest was invested at 7% simple interest.  At the end of the year, Tori had earned $496 in interest.  How much did she invest in each fund?

anonymous · Answer

@aliciabennett We need some variables and algebra to do this problem.

anonymous · Answer

I will pick $x$ and $x$ to be our variables.

anonymous · Answer

I mean $x$ and $y$

anonymous · Answer

this is exactly the way it is written in my book

anonymous · Answer

Yeah, the book is fine.

anonymous · Answer

I am thinking that at 5% she invested $3200 and at 7% she invested 4800

anonymous · Answer

Does it work out to the right total?

anonymous · Answer

Let $x$ be the amount in the $5\%$ account and $y$ be the ammount in the $7\%$ account.

anonymous · Answer

Yes

anonymous · Answer

"Tori invested $8000 in money market funds."

This gives us the equation:$$
x + y = $8000
$$

anonymous · Answer

Does this equation make sense?

anonymous · Answer

Okay nevermind.  Your solution is correct.  How did you get it?

campbell_st · Answer

well all you need is  let x be the 1st investment and then 8000 - x is the other investment

using I = Prn  

 $$ 496 = x \times 0.05 \times 1 + (8000 - x)\times 0.07 \times 1$$

$$496 = 0.05x + 560 - 0.07x$$

so your equation becomes 

496 = 560 - 0.02x

just solve for x which will tell you how much is invested at 5% and the balance is invested at 7%. 

hope this helps