Question 426823: A total of $12,000 is invested in 3 accounts earning 5%, 6%, and 7% annual interest. The combined interest for one year is $771. If the amount invested at 7% is three times the amount at 6%, find the amount invested at 5%.
Enter the amount rounded to the nearest dollar, without commas or the dollar symbol.
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! A total of $12,000 is invested in 3 accounts earning 5%, 6%, and 7% annual interest. The combined interest for one year is $771. If the amount invested at 7% is three times the amount at 6%, find the amount invested at 5%.
Enter the amount rounded to the nearest dollar, without commas or the dollar symbol.
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let x=dollar amount invested at 6%
3x=dollar amount invested at 7%
12000-3x-x=12000-4x=dollar amount invested at 5%
combined interest given=771
..
.06x+.07*3x+.05*(12000-4x)=771
.06x+.21x+600-.20x=771
.07x=171
x=171/.07=2442.85 (dollar amount invested at 6%)
12000-4x=2228.57 (dollar amount invested at 5%)
ans:
2228.57 is the dollar amount invested at 5%
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