Statistics: Informed Decisions Using Data (4th Edition)

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

Chapter 9 - Section 9.2 - Assess Your Understanding - Vocabulary and Skill Building - Page 448: 19b

Answer

Confidence interval: $100.417\lt x ̅\lt115.583$ The margin of error has increased.

Work Step by Step

$n=10$, so: $d.f.=n-1=9$ $level~of~confidence=(1-α).100$% $96$% $=(1-α).100$% $0.96=1-α$ $α=0.04$ $t_{\frac{α}{2}}=t_{0.02}=2.398$ (According to Table VI, for d.f. = 9 and area in right tail = 0.02) $Lower~bound=x ̅ -t_{\frac{α}{2}}.\frac{s}{\sqrt n}=108-2.398\times\frac{10}{\sqrt {10}}=100.417$ $Upper~bound=x ̅ +t_{\frac{α}{2}}.\frac{s}{\sqrt n}=108+2.398\times\frac{10}{\sqrt {10}}=115.583$
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