10 questions

23 minutes

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1. The registrar’s office at a university has noticed that a large number of students fail to report a change of address. The registrar decides to take a random sample of 150 students from the current directory of students and determine the number of students with the correct addresses on record. He then uses this information to construct a 95 percent confidence interval. Which of the following statements must be true?

2. In which of the following situations is a binomial model not an appropriate model to describe the outcome?

3. Which of the following statements about any two events A and B is true?

4. A newspaper reporter examined police reports of accidents during the past 12 months to collect data about the speed of a car and its stopping distance. The reporter then constructed a scatterplot and computed a correlation coefficient to show the relation between a car’s speed and its stopping distance. This is an example of

5. A company with offices in five different countries is interested in estimating the proportion of its employees in favor of banning smoking on the office premises. It is known that the views of people from different countries on issues like smoking tend to vary due to the influence of different local social structures. Which of the following is an appropriate sampling technique to use in this situation, and why?

6. In a clinic, 50 patients with sleep disorders are randomly assigned to one of two different groups. Patients in one group are given medication before bedtime. Patients in the other group are given blindfolds and played soft music at bedtime. Each patient is attached to a machine that records breathing patterns. From the patterns, it is possible to determine if the patient is awake or asleep. The data will be used to decide which method is more effective in helping patients with sleep disorders. Which of the following statements is correct in the context of this experiment?

7. Data were collected on two variables X and Y and a least squares regression line was fitted to the data. The estimated equation for this data is y = –2.29 + 1.70x. One point has x = 5, y = 6. What is the residual for this point?

8. The relation between studying time (in hours) and grade on a final exam (0-100) in a random sample of students in math class was found to be

Grade = 50.25 + 10.2 (h)

How will a student’s grade be affected if she studies for two hours?

9. A group of scientists wanted to estimate the proportion of geese returning to the same site for the next breeding season. Suppose they decided to increase the sample size from 200 to 2,000. How will this affect the distribution of the sample proportion?

10. A company has 400 employees. Their mean income is $20,500, and the standard deviation of their incomes is $3,750. The distribution of incomes is normally distributed. How many of the 400 employees do you expect to have an income of between $13,000 and $28,000?