SOLUTION: I can not figure out the formula for the folliwng problem. Robert inherited $4000 from grandmother. Part was invested at 5% while the rest was invested at 6.5%. The interest for t

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: I can not figure out the formula for the folliwng problem. Robert inherited $4000 from grandmother. Part was invested at 5% while the rest was invested at 6.5%. The interest for t      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 7241: I can not figure out the formula for the folliwng problem.
Robert inherited $4000 from grandmother. Part was invested at 5% while the rest was invested at 6.5%. The interest for the yearw as $227. How much was invested at 6.5%
Answer by ichudov(507) About Me  (Show Source):
You can put this solution on YOUR website!
say he invested X at 5% and Y at 6.5%. X+Y is 4,000. Interest is 0.05X+0.065Y = 227.
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
We'll use substitution. After moving 1*Y to the right, we get:
1%2AX+=+4000+-+1%2AY, or X+=+4000%2F1+-+1%2AY%2F1. Substitute that
into another equation:
0.05%2A%284000%2F1+-+1%2AY%2F1%29+%2B+0.065%5CY+=+227 and simplify: So, we know that Y=1800. Since X+=+4000%2F1+-+1%2AY%2F1, X=2200.

Answer: system%28+X=2200%2C+Y=1800+%29.