Walt made an extra $7000 last year from a part-time job. He invested part of the money at 10% and the rest at 7%. He made a total of $580 in interest. How much was invested at 7%? Select one:

Question

Tiana Kidd

Mathematics

5 December, 02:52

Walt made an extra $7000 last year from a part-time job. He invested part of the money at 10% and the rest at 7%. He made a total of $580 in interest. How much was invested at 7%? Select one:

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Answers (1)

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Jackrabbit · Answer 1

We know that

Interest = PNR / 100.

where P is the principal

R is the rate of Interest

N is the no of years the sum has been invested for.

Since N is not given we assume that to be 1

Therefore we have

10x / 100 + (7000 - x) * 7/100 = 580

Multiplying both sides by 100

10x + (7000-x) * 7 = 58000

simplifying

10x + 49000 - 7x = 58000

3x = 58000-49000

3x = 9000

x = 3000

therefore the sum of money invested at 7% = 7000 - 3000 = 4000