# Chapter 9 - Inferences Based on Two Samples - Exercises 9.1 - 9.29 - Learning the Mechanics - Page 423: 9.10f

Confidence interval is 17.49 - 22.51

#### Work Step by Step

From part (c), we have: $z_{α/2} = 1.96$ Margin of error (E) = 1.96 x $\sqrt {(100/100 + 64/100)}$ = 1.96 x 1.28 = 2.51 The endpoints of the confidence interval are: x̅1-x̅2 - E = 70 - 50 - 2.51 = 17.49 x̅1-x̅2 + E = 70 - 50 + 2.51 = 22.51

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