4
algebra

A total of $10,000 is invested, part at 4% and part at 6%. Total interest is $520. How much at 6%?

A

5000

B

4000

C

7000

D

6000

Correct Answer: D

Choice Choice D is the correct answer.

  1. Define: 6% = xx, 4% = 10000−x10000 - x.
  2. Equation: 0.06x+0.04(10000−x)=5200.06x + 0.04(10000 - x) = 520
  3. Simplify: 0.06x+400−0.04x=5200.06x + 400 - 0.04x = 520
  4. Combine: 0.02x=1200.02x = 120
  5. Divide by 0.02: x=6000x = 6000

Choice Choice B is incorrect because this is the amount at 4%.

Choice Choice A is incorrect because calculation error.

Choice Choice C is incorrect because calculation error.

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Linear Functions Set 35