College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter P, Prerequisites - Section P.9 - Modeling with Equations - P.9 Exercises: 25

Answer

Phyllis invested \$9000 at 4.5% and the rest (\$3000) at 4%.

Work Step by Step

Let $x$ be the amount invested at 4.5% and $12000-x$ be the amount invested at 4%. Thus the total earnings would be: Total earnings = $0.045*x+(12000-x)*0.04 = 525$ We solve for $x$: $0.045*x+480-0.04x=525$ $0.005*x+480=525$ $0.005*x=45$ $x=9000$ Thus Phyllis invested \$9000 at 4.5% and the rest (\$12000-\$9000=\$3000) at 4%.
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