A Gallup Poll conducted from February 28March 1, 2015, asked1015randomly selected adults, "How important is it that parents get their children vaccinatedextremely important, very important, somewhat important, or not at all important?" Gallup found that 54% of respondents said "extremely important."

Even though54%describes the relatively small sample of 1015 adults, compared to the274million adults in the United States, Gallup feels that on the basis of this one sample, they can conclude that the majority (more than50%) of American adults feel that it is extremely important for parents to get their childrenvaccinated. To see why, we need to understand the variability of random samples of size1015drawn from the samepopulation.

In thinking about Gallup's sample of size1015,we asked, "Could it happen that one random sample finds that54%of adults feel that childhood vaccination is extremely important and a second random sample finds that only42%do?" Look at the figure, which shows the results of1000samples of this size when the population truth is=0.5,or50%.Use the figure to support yourreasoning.

Would it be surprising if a sample from this populationgave54%?

Yes, because a value of54%is an unlikely sample proportion based on thehistogram.

Yes, because a value of54%is a not an unlikely proportion based on thehistogram.

No, because a value of54%is an unlikely sample proportion based on thehistogram.

No, because a value of54%is not an unlikely sample proportion based on thehistogram.

Would it be surprising if a samplegave42%?

Yes, because a value of42%is an unlikely sample proportion based on thehistogram.

Yes, because a value of42%is not an unlikely proportion based on thehistogram.

No, because a value of42%is not an unlikely proportion based on thehistogram.

No, because a value of42%is an unlikely sample proportion based on thehistogram.