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Q72.

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Precalculus Mathematics for Calculus

Found in: Page 690

Book edition 7th Edition

Author(s) James Stewart, Lothar Redlin, Saleem Watson

Pages 948 pages

ISBN 9781337067508

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Short Answer

A man invests his savings in two accounts, one
paying 6% and the other paying 10% simple interest per year.
He puts twice as much in the lower-yielding account because
it is less risky. His annual interest is $3520. How much did
he invest at each rate?

For the given investment problem the man invested $32,000 at a rate of 6% and $16,000 at a rate of 10%.

See the step by step solution

Step by Step Solution

TABLE OF CONTENTS :

TABLE OF CONTENTS

Step 1. Given information.

x = the amount invested in the first account.

y = the amount invested in the second account.

Step 2. Write down the concept.

x = 2y

x – 2y = 0 …….(1)

Also the total sum of interest earned would be,

0.06x + 0.1y = 3520 ……….(2)

Step 3. Determining the values

Solving equation (1) and (2) we have,

20 $\times$ equation (1) gives 1.2x + 2y = 70400

Now adding this to equation (2), we get

2.2x = 70400

x = 32000

Substituting this in (1)

2y = 32000

Y = 16000

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