Statistics: Informed Decisions Using Data (4th Edition)

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

Chapter 10 - Review - Review Exercises - Page 524: 20

Answer

There is statistical evidence that the proportion of students that return for their second year is greater than 0.52. Practically, the increase is not very significant. But, even a small increase is good thing. So, if it is not hard to implement the policies, it should be done.

Work Step by Step

$H_0:~p=0.52$ versus $H_1:~p\gt0.52$ $np_0(1-p_0)=2843\times0.52(1-0.52)=709.6128\gt10$ $p̂ =\frac{x}{n}=\frac{1516}{2843}=0.5332$ $z_0=\frac{p̂ -p_0}{\sqrt {\frac{p_0(1-p_0)}{n}}}=\frac{0.5332-0.52}{\sqrt {\frac{0.52(1-0.52)}{2843}}}=1.41$ Using the classical method: $z_α=z_{0.1}$ If the area of the standard normal curve to the right of $z_{0.1}$ is 0.1, then the area of the standard normal curve to the left of $z_{0.1}$ is $1−0.1=0.9$ According to Table V, the z-score which gives the closest value to 0.9 is 1.28. Since $z_0\gt z_α$, we reject the null hypothesis.
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