Basic College Mathematics (9th Edition)

Published by Pearson
ISBN 10: 0321825535
ISBN 13: 978-0-32182-553-7

Chapter 6 - Percent - 6.4 Using Proportions to Solve Percent Problems - 6.4 Exercises: 70

Answer

(a) The family saves $\$290$ each month. (b) $\$3480/year$

Work Step by Step

(a) We are told that the family spends $90\%$ of its earnings, which means it saves $100\%-90\%=10\%$. Since the total earnings are $\$2900$, we can find out the amount saved with a proportion: $\frac{x}{2900}=\frac{10}{100}=\frac{1}{10}$ We cross-multiply: $x*10=2900*1$ $x=2900/10=290$ Thus the family saves $\$290$ each month. (b) To find out the annual savings, we multiply the monthly savings by the number of months in a year (12): $290*12=\$3480/year$
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