Problem-Solving and Data Analysis practice question

Answer: A. It is plausible that the mean number of people per household in the city is between 2.4 and 2.8.

A confidence interval gives a range of plausible values for the population MEAN, with some uncertainty.

Why the other answers are wrong

B. 95% of the city's households have between 2.4 and 2.8 people.

The interval is about the mean, not about individual households (which have whole numbers of people).

C. Every household in the sample has between 2.4 and 2.8 people.

No household has 2.4 people; the interval describes the mean.

D. The mean for the city is certainly between 2.4 and 2.8.

A confidence interval is not a certainty; the true mean can lie outside it.

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