Statistics: Informed Decisions Using Data (4th Edition)

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

Chapter 11 - Section 11.4 - Assess Your Understanding - Applying the Concepts - Page 574: 18

Answer

$F_0\lt F_{1-α,n_1-1,n_2-1}$: null hypothesis is not rejected. There is not enough evidence to conclude that students who do not plan to apply for financial aid have a higher standard deviation on the SAT I math exam than students who plan to apply for financial aid.

Work Step by Step

$s_1,n_1~and~d.f._1$ refer to the "do not plan" group and $s_2,n_2~and~d.f._2$ refer to the "plan" group. $H_0:~σ_1=σ_2$ versus $H_1:σ_1\gtσ_2$ $F_0=\frac{s_1^2}{s_2^2}=\frac{123.1^2}{119.4^2}=1.06$ $d.f_1=n_1-1=35-1=34$ $d.f_2=n_2-1=38-1=37$ Right-tailed test: $F_{α,n_1-1,n_2-1}=F_{0.01,34,37}=2.54$ (According to table VIII, for $d.f._1=30$, the closest value to 34, $d.f._2=25$, the closest value to 37, and area in the right tail = 0.01) Since $F_0\lt F_{1-α,n_1-1,n_2-1}$, we do not reject the null hypothesis.
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