Statstics Test 1 Review - Chapter 1, 2 and 3

13. Two amateur gardeners are interested in comparing the yields of two varieties of tomatoes. They each have small backyard gardens. Each gardener is going to plant three plants of each variety in his garden. The first gardener will select six small areas in his garden for planting, then choose three of these at random for the three plants of the first variety and then use the remaining three for the second variety. The second gardener will follow the same procedure with his own randomization in his garden. At the end of the growing season they will compare the yields of the two varieties. In this example the gardens are a. blocks. b. a lurking variable. c. the explanatory variable

a is the correct answer

14. A researcher is interested in the cholesterol levels of adults in the city in which she lives. A cholesterol screening program is set up in the downtown area during the lunch hour. Individuals can walk in and have their cholesterol determined for free. The service is used by 173 people, and their average cholesterol is 217.8. The sample obtained is an example of a. a sample probably containing b. bias and undercoverage. a simple random sample because the experimenter did not know beforehand which individuals would come to the screening. c. a stratified sample of high- and low-cholesterol individuals.

a is the correct answer

15. Suppose you are going to roll a die 60 times and record , the proportion of times that a 1 or a 2 is showing. The sampling distribution of should be centered about a. 1/3. b. 1/6. c. 20.

a is the correct answer

6. I want to examine whether there is a relationship between a student's grade point average and after-college plans. For a visual display of the data I should choose a. side-by-side boxplots. b. a scatterplot. c. a back-to-back stemplot

a is the correct answer

11. A researcher wants to study the effect of regular exercise on cholesterol levels. The researcher compares the cholesterol levels of 50 people who belong to a local gym and exercise regularly with the cholesterol levels of 50 people from the community who did not exercise regularly. The cholesterol levels of the members of the gym were substantially lower. The researcher can conclude that a. belonging to a gym reduces cholesterol level. b. members of a local gym who exercised regularly had lower cholesterol levels than those in the community who did not exercise regularly. c. exercising regularly reduces cholesterol level.

b is the correct answer

2. A biology class has 201 students. The five-number summary for the midterm exam was 23, 51, 62, 78, 92 The student with the 92 found a grading error on her exam, and her correct grade was 95. There were no other grading errors. After correcting this student's paper, the five-number summary for the midterm exam will be: a. 3, 51, 62, 78, 92. b. 23, 51, 62, 78, 95 c. 23, 51, 62, 81, 95.

b is the correct answer

8. Which of the following does not have an error? a. The correlation between students' majors and their GPA is 0.67. b. The correlation between students' IQ scores and their foot size is 0.67. c. The correlation between students' incomes and their GPA is 1.12.

b is the correct answer

9. I want to examine the relationship between the number of calories/serving and the grams of fat/serving in breakfast cereals. The explanatory and response variables are a. calories/serving; grams of fat/serving. b. grams of fat/serving; calories/serving. c. I could use either one.

b is the correct answer

1. You receive a fax with six bids (in millions of dollars) 2.2, 1.3, 1.9, 1.2, 2.4, and x, where x is some number that is too blurry to read. Without knowing what x is, the median a. is 1.9. b. could be any number between 1.2 and 2.4. c. must be between 1.3 and 2.2.

c is the correct answer

10. A survey of 1000 adults ages 30 to 35 is conducted. The number of years of schooling and the annual salary for each person in the survey is recorded. The correlation between years of schooling and annual salary is found to be 0.27. Suppose instead the average salary of all individuals in the survey with the same number of years of schooling was calculated and the correlation between these averages and years of schooling was computed. This correlation would most likely be a. equal to 0.27. b. less than 0.27. c. larger than 0.27.

c is the correct answer

12. A study sponsored by American Express Co. and the French government tourist office found that old American stereotypes about French unfriendliness weren't true. The respondents were more than 1000 Americans who have visited France more than once for pleasure over the past two years. The results of this study are probably a. very inaccurate since the sample is only a small fraction of all Americans who have visited France. b. very accurate given the large sample size. c. biased, overstating the extent to which the old stereotypes weren't true.

c is the correct answer

3. The scores on a university examination are normally distributed with a mean of 62 and a standard deviation of 11. If the top 10% of students are given A's, what is the lowest mark that a student can have and still be awarded an A? a. 63.28 b. 70.97 c. 76.08

c is the correct answer

4. The lifetime of a 2-volt nonrechargeable battery in constant use has a Normal distribution with a mean of 516 hours and a standard deviation of 20 hours. Ninety percent of all batteries have a lifetime less than a. 517.28 hours. b. 536.00 hours'. c. 541.60 hours.

c is the correct answer

5. A major study examined the relationship between cause of death (heart attack, cancer, stroke, accident, etc.) and age. A good way to graphically represent the relationship is with a. a scatterplot. b. back-to-back stemplots. c. side-by-side boxplots.

c is the correct answer

7. If females of a certain species of lizard always mate with males that are 0.75 years younger than they are, what would be the correlation between the ages of these male and female lizards? a. -1 b. 0.75 c. 1

c is the correct answer