A poll was conducted in 2019 in which they surveyed people all over the United States and found that 69% of adults in the U.S. believe that global warming is happening. Assume that this is the population proportion of U.S. adults who believe global warming is happening (p= 0.69), and suppose we repeatedly select random samples of size 250, and ask them the same question.

(a) Find the mean, /, and standard error, / of the sampling distribution of sample proportions for the given n and p.

(b) Use the Empirical Rule to find the interval centered at p that contains approximately 99.7% of all sample proportions.

(c) Suppose that in a random sample of 250 people, 155 say that global warming is happening. Find the sample proportion and the z-score for this sample proportion.