Given a confidence interval (44.07, 80.97)

As confidence interval is \(\overline{x}=\pm E,(\overline{x}+E)-(\overline{x}-E)=2E\) where \(\overline{x}\) is mean price of sample of textbooks and E is margin of error.

Thus, \(E=\frac{80.97-44.07}{2}=18.45\)

Now, \(\overline{x} - E = 44.07\)

Hence, \(\overline{x} = 44.07 + 18.45 = 65.52\) is mean price of sample textbooks

Answer: \(E = 18.45\)

\(\overline{x} = 62.52\)

As confidence interval is \(\overline{x}=\pm E,(\overline{x}+E)-(\overline{x}-E)=2E\) where \(\overline{x}\) is mean price of sample of textbooks and E is margin of error.

Thus, \(E=\frac{80.97-44.07}{2}=18.45\)

Now, \(\overline{x} - E = 44.07\)

Hence, \(\overline{x} = 44.07 + 18.45 = 65.52\) is mean price of sample textbooks

Answer: \(E = 18.45\)

\(\overline{x} = 62.52\)