week5 MA215 discussion

asharpe

What is a confidence interval?
Let's say you made a confidence interval for a mean taken from the sample that is representative of the population. Will that confidence interval apply to the population or to the sample?
In the discussion for week 4, you rolled a pair of dice 10 times and calculated the average sum of your rolls. Then you did the same thing with 20 rolls. Use your results from the week 4 discussion for the average of 10 rolls and for the average of 20 rolls to construct a 95% confidence interval for the true mean of the sum of a pair of dice (assume s = 2.41).
What do you notice about the RANGE of the interval for the mean of 10 rolls versus the mean of 20 rolls? Finish this rule: As the samples size increases, the range of the confidence interval ______________ (increases/decreases - pick one).
Using your mean for 20 rolls, calculate the 90% confidence interval. Compare the range of the confidence interval for 90% to 95%. Finish this rule: As the confidence level increases, the range of the confidence interval _______ (increases/decreases - pick one).
In the project for this week, you are calculating confidence intervals for someone who is picking between the engineering major and the business major. You are trying to tell him/her what is likely to happen. Is it more helpful to have a large range or a narrow range in a confidence interval? Why

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