Elementary Algebra

Published by Cengage Learning
ISBN 10: 1285194055
ISBN 13: 978-1-28519-405-9

Chapter 4 - Proportions, Percents, and Solving Inequalities - 4.2 - Percents and Problem Solving - Problem Set 4.2 - Page 156: 38


The percent of change in the patient’s dosage is -25%. The dosage amount decreased by 25%.

Work Step by Step

To find the percentage change, we use the following formula: percentage change = $\frac{New\ amount\ -\ Original\ amount}{Original\ amount}$ $\times$ 100% The original dosage was 40 milligrams. The new dosage is 30 milligrams. We substitute these values into the formula to obtain: percentage change = $\frac{30\ -\ 40}{40}$ $\times$ 100% percentage change = $\frac{-10}{40}$ $\times$ 100% percentage change = -0.25 $\times$ 100% percentage change = -25% Because it is a negative number, it is a percent decrease.
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