Chapter 8, Problem T8.7SPT

To determine

To find: The 95% confidence interval using the same data.

Answer to Problem T8.7SPT

The correct option is (e).

Explanation of Solution

Given:

  $\begin{array}{l}\text{Confidence interval}=90\pm 30\\ \text{Confidence level }=90\%\end{array}$

It is known that the width of the confidence interval is positively related to the sample size. So, for the sample data at 95% confidence level the width of interval would get wider. In order to compute the confidence interval sample size must be known.

Hence, the correct option is (e).