 Unless the original distribution is already normal, we must have a sample size of n > 30.  If normal, there is no size requirement.

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Presentation transcript:

 Unless the original distribution is already normal, we must have a sample size of n > 30.  If normal, there is no size requirement

 Round to one decimal place beyond the original data set!

 The prefrontal cortex of the human brain is responsible for what is called executive function. Executive function relates to abilities to differentiate among conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectation based on actions, and social "control" (the ability to suppress urges that, if not suppressed, could lead to socially unacceptable outcomes).

 A brain researcher is trying to determine at what age the prefrontal cortex is fully developed in humans. He develops a specific test to determine if it is developed in a person, and brings back his 100 test subjects twice a year to check. He finds that his patients have an average age of 24.5 when their prefrontal cortex is fully developed with a standard deviation of 3.5 years. Give a 95% confidence interval for the actual average age in which a human’s prefrontal cortex is fully developed.

 The average incomes of the families of 25 randomly selected Bradley University students are listed below:  Determine a 99% confidence interval for the actual average income of a Bradley family

 Determine the necessary sample size to have a 95% confidence interval with a margin of error of 2.5 and a standard deviation of 2.

 Think of some sort of quantitative data that you can collect about your friends/classmates. (height, weight, age, allowance, number of pets, money in their wallet, size of family, etc.)  You must survey at least 10 people that are not in this class tonight!  You will survey your classmates at the start of class tomorrow.  Make sure you can justify why you chose the topic.

 P.352: 13, 15, 22, 25

 Got any questions???

 You have the first minutes to conduct your surveys with you classmates, make sure to record all data!  If you finish early start entering data in L1 of your calculator.

 Using the data you have collected, construct a confidence interval for the mean using any level of your choice!  Write neatly on notebook paper, leave space for short answer questions that are coming up.

 Why did you choose the topic you chose?  Why did you pick the confidence level you chose?  What did you learn about the topic?  Were you surprised by anything?  What population were you estimating for? ◦ Humans, OHS students, teenagers, etc?  How could you use this information in future?