The Gallup Poll asked a random sample of 1785 adults whether they attended church during the past week. Suppose that 40% of the adult population did attend. We would like to know the probability that an SRS of size 1785 would come within plus minus 3 percentage points of this true value.
If p-hat is the proportion of the sample who did attend church, what is the mean of the sampling distribution of p-hat? What is its standard deviation? Explain why you can use the formula for the standard deviation of p-hat in this setting (Rule of Thumb 1). Find the probability that p-hat takes a value between 0.37 and 0.43. Will an SRS of size 1785 usually give a result p-hat within plus or minus 3 percentage points of the true population proportion? Explain.