Simple Interest Problem

D

Dumbest Math Student Ever

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May 12, 2012
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I am a little lost on this problem and wonder if something might be missing or maybe I am on the right track and just underestimating myself.

You invested $6000 in two savings, some at 7% (simple interest) and the rest at 8.5%.
The total amount of interest from both accounts for one year was $398. How much
was invested in each account?

X+y(.07)+y+x(.085)=6398
X+.07y+.085x+y=6398
1.07y+1.085x=6398

1.07y=-1.085x+6398
____________
1.07
Y=
This is where I get stuck and I'm not sure if I'm on the right track or have used the wrong formula. Should I be using the SImple interest formula?
Thanks in Advance,
Jovanna
 
Dumbest Math Student Ever said:
I am a little lost on this problem and wonder if something might be missing or maybe I am on the right track and just underestimating myself.

You invested $6000 in two savings, some at 7% (simple interest) and the rest at 8.5%.
The total amount of interest from both accounts for one year was $398. How much
was invested in each account?

X+y(.07)+y+x(.085)=6398
X+.07y+.085x+y=6398
1.07y+1.085x=6398

1.07y=-1.085x+6398

At this point you need to invoke the other equation and substitute

x + y = 6000 → x = 6000 - y .................................................(1)

Use this expression for 'x' into the equation you derived:

1.07*y = -1.085*(6000 - y) + 6398 → 6510 - 6398 = 1.085 *y - 1.07*y ...... and continue.....


____________
1.07
Y=
This is where I get stuck and I'm not sure if I'm on the right track or have used the wrong formula. Should I be using the SImple interest formula?
Thanks in Advance,
Jovanna
Click to expand...

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I have the worst professor ever.

I literally communicated via email with my professor only to have him realize he made the mistake and the problem made NO SENSE. Thank you and Im sorry to waste your time.
 
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