Statistics: Informed Decisions Using Data (4th Edition)

Published by Pearson
ISBN 10: 0321757270
ISBN 13: 978-0-32175-727-2

Chapter 10 - Section 10.2 - Assess Your Understanding - Applying the Concepts - Page 494: 23

Answer

$0.47\gt Upper~bound$: null hypothesis is rejected. There is enough evidence to conclude that parents’ attitudes toward the quality of education in the United States has changed since August 2002.

Work Step by Step

$p̂ =\frac{x}{n}=\frac{437}{1013}=0.4314$ Required condition: $1013\times0.4314(1-0.4314)=1013\times0.4314(1-0.4314)=248.48\gt10$ $level~of~confidence=(1-α).100$% $95$% $=(1-α).100$% $0.95=1-α$ $α=0.05$ $z_{\frac{α}{2}}=z_{0.025}$ If the area of the standard normal curve to the right of $z_{0.025}$ is 0.025, then the area of the standard normal curve to the left of $z_{0.025}$ is $1−0.025=0.975$ According to Table V, the z-score which gives the closest value to 0.975 is 1.96. $Lower~bound=p ̂-z_{\frac{α}{2}}.\sqrt {\frac{p ̂(1-p ̂)}{n}}=0.4314-1.96\times\sqrt {\frac{0.4314(1-0.4314)}{1013}}=0.4009$ $Upper~bound=p ̂+z_{\frac{α}{2}}.\sqrt {\frac{p ̂(1-p ̂)}{n}}=0.4314+1.96\times\sqrt {\frac{0.4314(1-0.4314)}{1013}}=0.4619$ Since $0.47\gt Upper~bound$ (out of the 95% confidence inerval), we reject the null hypothesis.
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