ISU STAT 226 - Exam1practice (5 pages)

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Stat 226 Exam 1 Practice Questions 1 TRUE or FALSE Identify which of the following are valid statements and which ones are false a T F All density curves are symmetric b T F Prior to analyzing any data one should always check for outlying observations and if present delete these to avoid biased results c T F Dataset X has n 100 observations Suppose I order all observations from smallest to largest and obtain a value of 44 for the IQR If I increase the LARGEST observation by any positive number in Dataset X then the IQR will change d T F Dataset Y has n 100 observations all equal to 25 Dataset Z has n 50 observations all equal to 50 The variance of Dataset Y is equal to the variance of Dataset Z e T F The sampling distribution of the sample mean allows us to compute how likely it is to observe a sample mean falling within a particular range of values f T F The random variable Z can be described by a Standard Normal distribution The range of Z is between 3 49 and 3 49 i e Z can take on any value between 3 49 and 3 49 g T F In a histogram a larger bin width is associated with a bigger loss of information h T F When the sample size n increases the variance of the corresponding sampling distribution increases i T F Zip codes are an example of an ordinal categorical variable 2 Obesity Epidemic Revisited In 2010 body mass index BMI for male adults followed a Normal distribution with mean 27 8 and standard deviation 5 5 A man is considered obese if he has a BMI greater than 30 a The probability of a male adult from 2010 having a BMI greater than 30 i e classified as obese is 0 3446 Suppose I take a random sample of n men where n 1 What can you say about the probability that the mean BMI of the random sample is greater than 30 Circle One i The probability that the mean BMI for these n men is greater than 30 will be less than 0 3446 ii The probability that the mean BMI for these n men is greater than 30 will be more than 0 3446 iii The probability that the mean BMI for these n men is greater than 30 will be equal to 0 3446 iv There is not sufficient information to answer this question 1 b Suppose I take a simple random sample of 100 men from 2010 i Describe the sampling distribution of the mean BMI for samples of size 100 by answering the following questions a What is the shape of the sampling distribution Circle One Normal Approximately Normal Not Normal b What is the mean of the sampling distribution Do not round answer Final Answer c What is the standard deviation standard error of the sampling distribution Do not