SOLUTION: Suppose jodi invested $10,000 , part at 6% simple annual interest, and the rest at 9% simple annual interest. If you received $684 in simple interest after one year, how much did y

Question 5892: Suppose jodi invested $10,000 , part at 6% simple annual interest, and the rest at 9% simple annual interest. If you received $684 in simple interest after one year, how much did you invest at each rate?
My answer was:
$3999.60 at 6%
$5999.40 at 9%
Is this the right answer? please help me!
Answer by Abbey(339) (Show Source): You can put this solution on YOUR website!
You can check your answer by multiplication:
.06*3999.60 = 239.976
.09*5999.40 = 539.946
239.976+539.946 = 779.922 - not a correct answer because it should only total $684:
Let x = the amount jodi invested at 6%
.06x = the interest earned at 6%
Let 10000-x = the amount invested at 9% ($10000-the amount invested at 6%=the amount invested at 9%)
.08(10000-x)= the interest earned at 9%
6% interest + 9% interest = $684
.06x+.09(10000-x)=684
.06x+900-.08x=684
-.03x=684-900
-.03x=-216
x=7200
amount invested at 6%=7200
amount invested at 9% = 2800 (10000-7200)
check:
.06*7200=$432
.09*2800 = $252
432+252=$684

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