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Question 404445: The Gibsons invested $7000, part at 6% and the rest at 10% simple annual intrest. If they had reversed the amounts invested at each rate, they would have earned $120 less in annual intrest. How much was invested at each rate?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The Gibsons invested $7000, part at 6% and the rest at 10% simple annual intrest. If they had reversed the amounts invested at each rate, they would have earned $120 less in annual interest. How much was invested at each rate?
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Original Int: 0.06x + 0.10(7000-x)
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Reversed Int: 0.10x + 0.06(7000-x)
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Equation:
original - reversed = 120
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[0.06x + 0.10(7000-x)] - [0.10x + 0.06(7000-x)] = 120
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[-0.04x + 0.04(7000-x)] = 120
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-0.04x + 0.04*7000 - 0.04x = 120
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-0.08x = 120-0.04*7000
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-0.08x = -160
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x = $2000 (amt. invested at 6%)
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7000-x = $5000 (amt. invested at 10%)
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Cheers,
Stan H.
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