An October 1-10, 2019, Gallup poll asked 1,526 U.S. adults how much they planned to personally spend on Christmas gifts this year. The report cited an average of $942.

If you wanted to answer the question "Do U.S. adults spend significantly less than $950 on average for Christmas gifts?," a confidence interval could answer that question. If we look at the confidence interval that was constructed assuming the standard deviation of spending to be $150, we get a confidence interval entirely below $950. So, yes, on average U.S. adults are spending significantly less than $950 on Christmas gifts. While this may be a statistically sig- nificant finding giving us strong evidence against the average being $950, it doesn't mean that the average amount is far less than $950. The upper end of the confidence interval is $949.53, only 47 cents below $950. The margin of error of the interval is about $7 arguably less than would be spent on one additional gift. See Example 2.4 for more on this. Key Idea Especially with large sample sizes, even a fairly small difference between an observed and hypothesized value can be statistically significant. In such cases a confidence interval for the parameter can help to decide whether the difference is large. The Gallup poll did give us a bit more information; see Table 3.4.2. TABLE 3.4.2 Categorized responses to how much money respondents expected to spend on Christmas gifts 2019 (Gallup.com) $1,000 or Mean Mean more $500-999 $250-499 $100-249 Under $100 No opinion Median (w/zero) (w/o zero) 2019 Oct 1-10 37 21 12 15 10 $500 $942 $1.004 10. Based on this information, which appears to be a more reasonable guess ($150 or $300) for the sample standard deviation? Explain your reasoning