Introductory Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-805-X
ISBN 13: 978-0-13417-805-9

Chapter 2 - Section 2.1 - The Addition Property of Equality - Exercise Set: 65

Answer

According to the formula, 49% had an average grade of A in 2010. The formula overestimates the percent displayed on the graph by 1%.

Work Step by Step

To find x, the number of years after 1980, subtract 1980 from the given year. Substitute for x and use the addition property of equality to solve the equation for p. $p-0.8x=25$ $p-0.8(2010-1980)=25$ $p-0.8(30)=25$ $p-24=25$ $p-24+24=25+24$ $p=49$ The graph shows the actual percentage was 48%, a difference of 1%. Since the actual number is smaller, the formula overestimates the percentage.
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