SOLUTION: If 500 is invested at 6% interest, how much additional money must be invested at 9% so that the total return for both investments averages 8% ?

SOLUTION: If 500 is invested at 6% interest, how much additional money must be invested at 9% so that the total return for both investments averages 8% ?

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Question 161570: If 500 is invested at 6% interest, how much additional money must be invested at 9% so that the total return for both investments averages 8% ?
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
500*.06+.09x=.08(500+x)
30+.09x=40+.08x
.09x-.08x=40-30
.01x=10
x=10/.01
x=1,000 must be invested @ 9%.
Proof:
500*.06+.09*1,000=.08(500+1,000)
30+90=.08*1,500
120=120
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