The Gallup Poll asked a probability sample of 2500 U.S. adults whether they used a credit...

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  1. The Gallup Poll asked a probability sample of 2500 U.S. adultswhether they used a credit card to pay for groceries that week.Suppose that 25% of the adult population did. We would like to knowthe probability that an SRS of size 2500 would come within plus orminus 2 percentage points of this true value.
    1. If p-hat is the proportion of the sample who did use a creditcard to pay for groceries, what is the mean of p-hat? (2points)

    2. What is the standard deviation of p-hat? (2 points)

    3. Explain why you can use the formula for the standard deviationof p-hat in this setting.(check that the population is at least 10times larger than the sample) (2 points)
    4. Check that you can use the normal approximation for thedistribution of p-hat.(2 points)

    5. Find the probability that p-hat takes a value between 0.23 and0.27. (4 points)

Answer & Explanation Solved by verified expert
3.8 Ratings (735 Votes)
a p 025b sqrtp1 p sqrt025 0752500 0009c When the    See Answer
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