STAT 2103 Lecture Notes - Lecture 17: Confidence Interval, Null Hypothesis, Fair Coin
4 Apr 2018
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Stat 2103 lecture 17 inference for proportion cont"d. Confidence interval: the confidence interval is of the form, estimate z*std. dev, recall that the standard deviation of p is, since p is unknown, we replace it by p, z statistic. Example: 73% of freshman responding to a national survey identified financial independence as an important goal. A university finds that 132 of a srs of 200 freshman say that this goal is important: give a 95% c. i. for the proportion of freshman at the university who identify financial independence as an important goal. In a random sample of 484 consumers, 257 are optimistic about the economy. Find the 90% confidence interval for the proportion of all consumers who are optimistic about the economy. Buffon tossed a coin 4040 times and got 2048 heads. Is this evidence at the 5% level that the coin was not a fair coin: hypotheses, h0: p = 0. 50, ha: p 0. 50,
