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Statistics - Hypothesis Testing

1. NBC TV news, in segment on the price of gasoline, reported last evening that the mean price nationwide is $2.50 per gallon for self-serve regular unleaded. A random sample of 35 stations in Milwaukee, Wisconsin, area revealed that the mean price was $2.52 per gallon and that the standard deviation was $0.05 per gallon. At the .05 significance level, can we conclude that the price of gasoline is higher in the Milwaukee area? Determine the p-value.

2. receives an average of 6.5 returns per day from online shoppers. For a sample of 12 days, it received the following number of returns.
0 4 3 4 9 4 5 9 1 6 7 10
At the .01 significance level, can we conclude the mean number of returns is less than 6.5?

3. Traditionally, two percent of the citizens of the United States live in a foreign country because they are disenchanted with U.S. politics or social attitudes. In order to test if this proportion has increased since the September 11, 2001, terror attack, U.S. consulates contacted a random sample of 400 of these expatriates. The sample yields 12 people who report they are living overseas because of political or social attitudes. Can you conclude this data shows the proportion of political motivated expatriates has increased? Use the 0.05 significance level.


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