Question

The accompanying data represent the total travel tax​ (in dollars) for a​ 3-day business trip in 8 randomly selected cities. A normal probability plot suggests the data could come from a population that is normally distributed. A boxplot indicates there are no outliers. Complete parts​ (a) through​ (c) below. 67.51,79.13,69.76,83.95,80.71,86.93,101.76,98.47 (b) Construct and interpret a 95​% confidence interval for the mean tax paid for a​ three-day business trip. Select the correct choice below and fill in the answer boxes to complete your choice. ​(Round to two decimal places as​ needed.) A. The travel tax is between ​$ and ​$ for ​% of all cities. B. One can be % confident that the mean travel tax for all cities is between ​$ and  ​$. C. There is a % probability that the mean travel tax for all cities is between ​$ and ​$. D. One can be % confident that the all cities have a travel tax between ​$ and ​$. ​(Round to two decimal places as​ needed.) What would you recommend to a researcher who wants to increase the precision of the​ interval, but does not have access to additional​ data? A. The researcher could decrease the sample standard deviation. B. The researcher could increase the sample mean. C. The researcher could decrease the level of confidence. D. The researcher could increase the level of confidence.

Answer 1

For increasing the precision of CI without additional data, the researcher can always increase the level of confidence. Say for example from 95% confidence to 99% confidence.

Option D