Question

Suppose that a company claims that its air fresheners last 23 days, on average. You take many large samples, and find, each time, that the mean number of days of the sample is outside the 95% confidence interval. Based on this information alone, which of the following is probably not the mean number of days that the company's air fresheners last?
A. 19 B. 21 C. 23 D. 17

Answer 1

The answer is C 23. The problem says that "the mean number of days of the sample" is outside the confidence interval. The mean number of days of the sample is equal to 23. If 23 is outside the confidence interval, this is probably not the mean number of days that the company's air fresheners last.