VCU STAT 210 - Test 6 Practice Test #3 (1) (4 pages)

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Test 6 Practice Test #3 (1)



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Test 6 Practice Test #3 (1)

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Pages:
4
School:
Virginia Commonwealth University
Course:
Stat 210 - Basic Practice of Statistics
Basic Practice of Statistics Documents

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Test 6 Practice Test 3 1 What is the point estimate of the population mean A 0 2 B Z C X D t E s In the current chapter covering statistical inferences on means all of the procedures we have discussed sampling distributions confidence intervals and statistical tests have involved two assumptions What are those two assumptions In the fall of 2011 VCU launched Spit for Science the VCU Student Survey www spit4science vcu edu This project is following the 2011 VCU freshman class across its college years and will also enroll new VCU freshman classes over the next few years The goal of the project is to understand how genetic and environmental factors come together to influence a variety of health related outcomes in the VCU undergraduate population 3 Since Spit for Science data is only collected for students in the 2011 VCU freshman class most of them are similar in age Suppose that when the project began the ages in months of all students in the 2011 VCU freshman class are skewed slightly to the right with a mean of 219 months and a standard deviation of 8 months If a simple random sample of 44 students in the 2011 VCU freshman class is selected and the age in months of each at the beginning of the program determined describe completely the sampling distribution of in the 2011 VCU freshman class X the resulting mean age of this sample of 44 students 4 Data was collected on multiple days and of interest is to estimate the mean number of students from which data has been collected each day since the project began For this problem only assume that the standard deviation of the number of students from which data has been collected each day since the project began for all days is 14 7 students What is the minimum number of days that would need to be selected for data collection to allow the calculation of a 99 confidence interval with margin of error no greater than 5 5 students Please circle your final answer 5 A simple random sample of 50 days was selected and the number of students from which data was collected each day was recorded The mean number of students per day for this sample of 50 days was 21 4 students with a standard deviation of 5 2 students and the distribution is skewed to the right If appropriate use this information to calculate and interpret a 99 confidence interval for the mean number of students from which data has been collected each day since the project began 6 In question 5 a confidence interval was computed based on a sample of 50 days If the number of days in the sample were decreased to 30 what impact would this have on the margin of error and width of the confidence interval A The margin of error would increase and the width would decrease B The margin of error would decrease and



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