The Basic Practice of Statistics 7th Edition

Published by W. H. Freeman
ISBN 10: 146414253X
ISBN 13: 978-1-46414-253-6

Chapter 26 - Inference for Regression - Apply Your Knowledge - Page 628: 26.13b

Answer

$(62.97136,68.99974)$

Work Step by Step

The degree of freedom is the sample size minus $2$: $df=n-2=29-2=27$. The critical value is given in the row $df=27$ and in the column with $c=0.95$ of the table. Thus $t=2.052$. The confidence interval is then: $b\pm tSE_b=65.9855\pm2.052\cdot1.469$, thus the confidence interval is $(62.97136,68.99974)$
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