ST 311 Practice Final Exam Multiple Choice Fill in the circle for one answer only 1 A 95 confidence interval for 1 2 is found to be 5 12 2 46 Which of the following statements are true o A two sided hypothesis test for the difference in these means would be rejected at 0 01 o A two sided hypothesis test for the difference in these means would be rejected at 0 10 o We can conclude that 1 2 o We do not have enough evidence to support the alternative hypothesis 1 2 0 at 0 05 2 A medical journal describes a study in which subjects who have a seizure disorder were randomly assigned to two different treatments 1 no treatment and 2 a high dose of vitamin C The subjects were observed for a year and the number of seizures for each subject was recorded Identify the response variable of this study o subjects who recently had a seizure o the number of seizures during the time of the study o whether no treatment or a high dose of vitamin C was given o subjects receiving a high dose of vitamin C 3 A researcher testing a new medication for attention deficit disorder randomly assigns half of the participants to get the actual medication and half to get a sugar pill Neither the researcher nor the participants know who is getting what This study design will o increase researcher bias o increase dropout o reduce participant and researcher bias o reduce undercoverage 4 Which of the following statements are correct about a x value whose corresponding z score is z 1 o The x value is 1 standard deviation above the mean o The x value is in the 1st percentile o The x value is in the 99th percentile o The mean is 1 standard deviation above the x value Page 1 of 10 ST 311 Practice Final Exam 5 Which of the following is NOT a method for assigning subjects to treatment groups o Block Design o Completely Randomized Design o Stratified Random Sampling o Matched Pairs Design 6 In a study of the asking price for a sample of used cars a regression model is developed to predict the asking price in USD by using mileage in 1000 miles as a predictor The fitted least squares line is 321582 0 53 Which of the following is the correct interpretation of the slope 0 53 o Increasing mileage by 1000 miles will lead to a decrease in asking price for used cars by 0 53 o For every additional 530 miles in used car mileage we expect the asking price to decrease by 1 o For every additional dollar in asking price we expect mileage to decrease by 530 miles on o For every additional 1000 miles in used car mileage we expect the asking price to decrease by average 0 53 on average 7 According to a beer company the mean annual consumption of beer per person in the U S is 25 0 gallons A researcher randomly sampled 500 adults in Raleigh and yielded a mean annual beer consumption of 27 4 gallons He wants to perform a hypothesis test to decide whether the mean consumption in Raleigh exceeds the national mean Which set of hypotheses would be appropriate o 0 25 25 o 0 27 4 27 4 o 0 27 4 27 4 o 0 25 25 o P value is the proportion of the null distribution that is more extreme than the observed test o If the p value is small the statistic is unusual under the null hypothesis o If the p value is large the null hypothesis is appropriate for this population o If the p value is large we fail to reject the null hypothesis statistic 8 Which of the following is FALSE about p values Page 2 of 10 ST 311 Practice Final Exam 9 Below is the boxplot of average wind speed every day in miles hour at LaGuardia Airport New York from May 1 1973 to September 30 1973 Which of the following statements is TRUE based on the boxplot o The mode of the wind speed is about 10 miles hour o The mean is smaller than the median of the wind speeds o The mean is larger than the median of the wind speeds o The relationship between the mean and median of the wind speeds is not clear from the boxplot 10 Suppose a researcher wants to run a hypothesis test on the relationship between the amount of time studying and exam scores of students in ST 311 0 1 0 1 1 0 The test statistic was found to be significant which of the following would be the correct conclusion o There is no significant correlation between the amount of time studying and exam scores o There is a significant correlation between the amount of time studying and exam scores but the o The slope and the correlation between the amount of time studying and exam scores are both o The slope is significant but there is no correlation between the amount of time studying and slope is not significant significant exam scores 11 Chad is confused about how much money alligator wrestlers make He heard on a credible news channel that alligator wrestler salaries follow a highly right skewed distribution Which of the following salary summaries best estimates what Chad should expect to make as an alligator wrestler o Mean o Interquartile Range o Standard Deviation o Median Page 3 of 10 ST 311 Practice Final Exam 12 Historically 10 of the world s population dislikes cilantro I want to test whether the percentage of people who dislike cilantro has decreased I take a random sample of 200 individuals and find that 15 of these individuals dislike cilantro What is the approximate distribution of this sample proportion o Normal with a mean of 0 10 and a standard deviation of o Normal with a mean of 0 075 and a standard deviation of o t distribution with a mean of 0 10 and a standard deviation of o Normal with a mean of 0 and a standard deviation of 1 200 0 10 0 90 0 075 0 925 200 0 10 0 90 200 13 Which of the following is true about the correlation coefficient in regression o The correlation coefficient ranges from 0 to 1 o If the correlation coefficient is close to 1 it means that the predictor variable causes changes in o A negative correlation coefficient means that there is a weak correlation between X and Y o Higher absolute values of the correlation coefficient mean that more of the variability in Y can the response variable be explained by the model 14 A researcher wants to determine the proportion of a population that are obese He realizes that the population can be subdivided into income status Low Medium and High Which of the following sampling schemes is more appropriate for this study o Simple Random Sampling o Stratified Sampling o Systematic Sampling o Cluster Sampling 15 Which of the following is true about …