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The local electric company says that customers pay less than $200 per month on average. A local reporter is suspicious of these claims and thinks that customers are spending more than $200 per month. A random sample of 35 customers bills during a given month is taken with a mean of 220 and a standard deviation of 45. Create a hypothesis test from the perspective of the reporter to test the claims of the company under a 5% significance level.
Compute the power of the hypothesis test at detecting a mean of $220. (Make sure to draw a picture)
A population of people has incomes with a standard deviation of σ=$9000. A random sample of 25 people had a mean income of $54,800. Perform a hypothesis test using a significance level of .05 to see if this data provides statistically significant evidence that the mean salary is different than $60,000.
What is the power of the test at detecting a mean income of $ $ 57000$?
Given two proportions ˆp1=.25 and ˆp2=.30 from sample size n1=35 and n2=55. Calculate a 90% confidence interval.
Given two proportions ˆp1=.25 and ˆp2=.30 from sample size n1=35 and n2=55. Perfrom a hypothesis test to see if the data provides evidence that there is a difference int the two proportions.
True/False: A large t-score corresponds to a large p-value
True/False: In a one tailed test we compute a t-score of 1.7. With a 10% significance level we fail to reject the null hypothesis.
Describe a Type I error in the context of problem one
In a random sample of 1000 students, ˆp=0.8 (or 80%) were in favor of longer hours at the school library. Find the standard error of ˆp.
When should you use a pooled proportion?
Null and alternate hypothese are statements about: