Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter P - Section P.9 - Linear Inequalities and Absolute Value Inequalities - Exercise Set - Page 140: 120


The least amount of percentage is $95$%

Work Step by Step

First, let $x$ be the grade on the final examination. Then from the asked problem we have the inequality: $ \frac{0.86+0.88+0.92+0.84+2x}{6} \geq 0.90$ Next, all we have to do is solve the inequality. $ \frac{0.86+0.88+0.92+0.84+2x}{6} \geq 0.90$ $ \frac{3.50+2x}{6} \geq 0.90$ Multiply with $6$ on both sides. $ \frac{3.5+2x}{6}\times6 \geq 6\times0.90$ $ 3.50+2x \geq 5.40$ Subtract $3.50$ on both sides. $ 3.50+2x-3.50 \geq 5.40-3.50$ $ 2x \geq 1.9$ Divide with $2$ on both sides. $ \frac{2x}{2} \geq \frac{1.9}{2}$ $ x \geq 0.95$ Which is our solution.
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