SOLUTION: Stan invested $5,000, part at 8% and part at 17%. If the total interest at the end of the year is $490, how much did he invest at 8%? I got 3000.00 is this correct?

Question 55083: Stan invested $5,000, part at 8% and part at 17%. If the total interest at the end of the year is $490, how much did he invest at 8%? I got 3000.00 is this correct?
Answer by Hook(36) (Show Source): You can put this solution on YOUR website!
Big picture...why didn't Stan invest all his money at 17%? Don't take investment advice from Stan.

Ok..let's make up some variables to start:
We'll call x the amount that Stan invested at 8% and y the amount that he invested at 17%.
We know he invested 5 bills, so we get the following equation:

Also, his combined interest income was $490. So 8% of x plus 17% of y must be $490. In math-speak:

Here, we've got the following system of equations:

I'll use the substitution method and solve for x in the first equation

Now, I'll plug that into the second equation

Alright! y = 1000!
if we plug that into , we get

Ok. My answers are different than yours. I'll check my work.
CHECK:
Using the second original equation:

Check!
Stan invested $4000 at 8%. Dumbass. Don't let Stan run your investments.

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