STAT 200 Fall 2016 Quiz #3 Answer all 20 questions. Each question is worth 4 points, and the maximum score for the quiz is 80 points. Make sure your answers are as complete as possible and show your work/argument. In particular, when there are calculations involved, you should show how you come up with your answers with critical work and/or necessary steps. 1. A researcher believed that women in their 20s drank more soda per day than men. Which of the following was the null hypothesis? a. The amount of Soda women drank per day was greater than the amount of Soda men drank per day b. The amount of Soda women drank per day was equal to the amount of Soda men drank per day c. The amount of Soda women drank per day was smaller than the amount of Soda men drank per day d. The amount of Soda women drank per day was greater than or equal to the amount of Soda men drank per day 2. A professor assumed there was a correlation between amount of French fries consumed per week by mid-age women and their blood cholesterol level. The null hypothesis was that the population correlation was: a. Positive 1.0 b. Negative 1.0 c. Zero d. Positive 0.50 3. Conventionally, the null hypothesis will be rejected if the probability value is: a. Greater than 0.05 b. Less than 0.05 c. Greater than 0.95 d. Less than 0.95 4. A high school teacher hypothesized that in her class, boys were taller than girls. If the probability value of her null hypothesis is 0.34, it means: a. We failed to reject the null hypothesis b. Boys were significantly taller than girls c. Girls were significantly taller than boys d. Her null hypothesis was rejected 5. Which of the following can increase the rate of Type I error? a. Adjusting the significant level from 0.01 to 0.05 b. Adjusting the significant level from 0.05 to 0.01 c. Increase the level d. Increase the power 6. ___ is the probability of rejecting a false null hypothesis. a. 1-; b. ; c. ; d. 1- ; 7. A student hypothesized that in the US adult population, women drank the same amount of water per day as men per kg of body weight as the two-tailed null hypothesis. The probability value for his null hypothesis was 0.02. So he concluded that: a. Women drank a greater amount of water per kg of body weight per day than men b. Men drank a greater amount of water per kg of body weight per day than women c. Women drank the same amount of water per kg of body weight per day as men d. He rejected the null hypothesis that women drank the same amount of water per kg of body weight per day as men 8. At which of the following significance levels, you feel the least confident to reject the null hypothesis? a. 0.05 b. 0.01 c. 0.15 d. 0.10 9. A student hypothesized that on a Chemistry test, the mean score of his class was 80. If the 95% confidence interval of the grades was (75, 86), can you reject the null hypothesis that the mean score was equal to 80 at 0.05 level? a. Yes b. No 10. A teacher hypothesized that the average of grades for a math test was 79. Imagine 20 students took the test and the 95% confidence interval of grades was (83, 90). Can you reject the teacher's null hypothesis at 95%? a. Yes b. No c. We cannot tell from the given information 11. Imagine that a researcher wanted to know the average weight of 5 th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. What's the sample standard deviation? (Show work) 12. Imagine that a researcher wanted to know the average weight of 5 th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. What's the standard error of the mean? (Show work) 13. Imagine that a researcher wanted to know the average weight of 5 th grade boys in a high school. He randomly sampled 5 boys from that high school. Their weights were: 120 lbs., 99 lbs, 101 lbs, 87 lbs, 140 lbs. The researcher posed a null hypothesis that the average weight for boys in that high school should be 100 lbs. What is the absolute value of calculated t that we use for testing the null hypothesis? (Show work) 14. Imagine a researcher posed a null hypothesis that in a certain community, the average energy expenditure should be 2,100 calories per day. He randomly sampled 100 people in that community. After he computed the t value by calculating a two-tailed t-statistic, he found that the probability value was 0.10. Thus, he concluded: a. The average energy expenditure was bigger than 2,100 calories per day b. The average energy expenditure was smaller than 2,100 calories per day c. He could not reject the null hypothesis that the average energy expenditure was 2,100 calories per day d. The average energy expenditure was either more than 2,100 calories per day or less than 2,100 calories per day 15. Compared to the normal distribution, the t distribution has ___ values at the top and ___ at the tails. a. More; less b. More; more c. Less; less d. Less; more 16. In order to test if there is a difference between means from two populations, which of following assumptions are NOT required? a. The dependent variable scores must be a continuous quantitative variable. b. The scores in the populations are normally distributed. c. Each value is sampled independently from each other value. d. The two populations have similar means 17. A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 120 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was 5.0. The mean score for boys was 65 and the standard deviation of mean was 6.0. What's the absolute value of the difference between means? (Show work) 18. A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 100 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was 5.0. The mean score for boys was 65 and the standard deviation of mean was 5.0. What is the standard error of the difference in means? (Show work) 19. A researcher posed a null hypothesis that there was no significant difference between boys and girls on a standard memory test. He randomly sampled 100 girls and 100 boys in a community and gave them the standard memory test. The mean score for girls was 70 and the standard deviation of mean was 5.0. The mean score for boys was 65 and the standard deviation of mean was 5.0. What's the t-value (two-tailed) for the null hypothesis that boys and girls have the same test scores? (Show work) 20. Which of the following involves making pairwise comparisons? a. Comparing the standard deviation of GRE grades between two states b. Comparing the variance of the amount of soda consumed by boys and girls in a high school c. Comparing the mean weight between children in grades 2, 3, 4 and 5 d. Comparing the number of restaurants in New York and Boston