Statistics: Informed Decisions Using Data (4th Edition)

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

Chapter 12 - Section 12.1 - Assess Your Understanding - Applying the Concepts - Page 597: 22a

Answer

$X^2\lt X_α^2$: the null hypothesis is not rejected. There is not enough evidence to conclude that the die is loaded.

Work Step by Step

$H_0:$ the die is not loaded. That is, $P(1)=P(2)=P(3)=P(4)=P(5)=P(6)=\frac{1}{6}$ $H_1:$ the die is loaded. Total:400 dice rolls. Expected count of 1: $400\times\frac{1}{6}=66.667$ Expected count of 2: $400\times\frac{1}{6}=66.667$ Expected count of 3: $400\times\frac{1}{6}=66.667$ Expected count of 4: $400\times\frac{1}{6}=66.667$ Expected count of 5: $400\times\frac{1}{6}=66.667$ Expected count of 6: $400\times\frac{1}{6}=66.667$ $X^2=Σ\frac{(O_i-E_i)^2}{E_1}=\frac{(62-66.667)^2}{66.667}+\frac{(76-66.667)^2}{66.667}+\frac{(76-66.667)^2}{66.667}+\frac{(62-66.667)^2}{66.667}+\frac{(57-66.667)^2}{66.667}+\frac{(67-66.667)^2}{66.667}=4.670$ $k=6$. So, $d.f.=6-1=5$ $X_α^2=X_{0.01}^2=15.086$ (According to Table VII, for d.f. = 5 and area to the right of critical value = 0.01) Since $X^2\lt X_α^2$, we do not reject the null hypothesis.
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