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 - Page 70: 23



Work Step by Step

The average of the exams is: Average score: $\frac{82+75+71+2*final}{5}$ Where $final$ is her final score. We multiply by 2 because the final score counts twice and we divide by $5$ because the final adds 2 more test scores to the previous 3. The average score needs to be 80: $80=\frac{82+75+71+2*final}{5}$ We solve for the final score: $final=\frac{80*5-(82+75+71)}{2}=86$ Thus her final score needs to be over 86% for Linh to get 80% is the class.
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