31.Data inferences.docx

Data inferences 1. A random sample of 35 four-door passenger vehicles had a mean gas mileage, in miles per gallon (mpg), of 25.9 mpg. The estimate had a margin of error of 2.6 mpg at a 98% confidence level. Of the following, which is most plausible value for the true mean of the mileage of four-door passenger vehicles in general? A. 24 mpg B. 29 mpg C. 32 mpg D. 35 mpg Correct answer: A Difficulty level: 2 2. Based on random samples of river heights, oceanographers estimate that 4,800 cubic kilometers (km3) of freshwater is discharged into the Arctic Ocean annually. The estimate has a margin of error of 240 km3 at the 90% confidence level. Which of the following is the most reasonable claim about the volume of freshwater discharged annually into the Arctic Ocean? A. It is between 4,800 and 5,040 km3. B. It is between 4,560 and 5,040 km3. C. It is between 240 and 4800 km3 . D. It is between 240 and 4320 km3 . Correct answer: B Difficulty level: 2 3. A survey of 9,000 randomly selected dentists practicing in the United States (US) found that 3,600 of them used text messaging to remind clients of upcoming appointments. If there were 147,000 practicing dentists in the US, approximately how many of them used text messaging for that purpose? A. 12,600 dentists B. 58,800 dentists C. 159,600 dentists D. 367,500 dentists Correct answer: B Difficulty level: 2 4. A random sample of international flights in 2013 showed that 79% of the flights arrived within 15 minutes of their scheduled arrival time, and this estimate had a margin of error of 3% at a 95% confidence level. Which of the following conclusions is best? A. Exactly 79% arrived within 15 minutes of their scheduled times. B. Exactly 76% arrived within 15 minutes of their scheduled times. C. Between 76% and 82% arrived within 15 minutes of their scheduled times. D. Between 92% and 98% arrived within 15 minutes of their scheduled times. Correct answer: C Difficulty level: 2 5. In a poll of 1,578 randomly selected American adults, 44.8% of the respondents said that airlines should allow in-flight calls on airplanes. The results had a margin of error of 2.5% at a 90% confidence level. Which of the following is most likely to be equal to the percentage of all American adults who would say that airlines should allow in-flight calls? A. 40% B. 43% C. 48% D. 90% Correct answer: B Difficulty level: 2 6. In a study of 40 randomly selected captive Octopus vulgaris, researchers found that the octopi could learn to integrate visual and tactile information to find food after a mean of 119 trials. The estimate had a margin of error of 18 trials at a 95% confidence level. Which of the following is the most reasonable conclusion about the number of trials it would take all captive Octopus vulgaris in general to learn to find the food? A. The evidence suggests that half of them would require 119 or fewer trials. B. The evidence suggests that the mean number of trials would be 119 trials. C. The evidence suggests that the mean number of trials would be between 119 and 137 trials. D. The evidence suggests that the mean number of trials would be between 101 and 137 trials. Correct answer: D Difficulty level: 3 7. Researchers measured the heart rates of several randomly selected astronauts exercising on stationary bicycles during long-term space missions. The researchers found the mean heart rate of the astronauts was 155 beats per minute with a margin of error of 12 beats per minute at a 90% confidence level. Which of the following is the most plausible value for the mean heart rate of all astronauts exercising on stationary bicycles during long-term space missions? A. 130 beats per minute B. 140 beats per minute C. 160 beats per minute D. 175 beats per minute Correct answer: C Difficulty level: 3 8. In a poll of 14,697 randomly selected adults in the United States, those polled spent an average of $95 per day in November of last year, as compared with $91 per day in November two years ago. The estimates had a margin of error of $4 at the 95% confidence level. Which of the following is a reasonable claim to make based on this sample? A. All adults in the United States spent between $91 and $99 daily last November. B. 95% of adults in the United States spent between $91 and $99 daily last November. C. It is plausible that average daily spending of adults in the United States remained the same in November of last year as it was in November two years ago. D. Between 91% and 99% of adults in the United States spent $4 more daily last November than in November two years ago. Correct answer: C Difficulty level: 3 9. In a particular county, a sample of the population showed that 84% of the households lived in the same residence as they had the previous year. The estimate had a margin of error of 1.5% at the 90% confidence level. If the county has 50,000 households, which of the following best estimates the number of households that lived in the same residence as they had the previous year, at the 90% confidence level? A. 34,500 to 49,500 residents B. 37,500 to 50,000 residents C. 41,250 to 42,750 households D. 44,250 to 45,750 households Correct answer: C Difficulty level: 3 10. Prior to the 2014 elections, 1,000 randomly selected Louisiana voters were surveyed about what single issue would most likely influence their vote. Of those surveyed, 560voters answered that the state of the economy would most influence their vote. Based on this information, which statement about all voters in Louisiana is most appropriate? A. Exactly 56% of all Louisiana voters thought the state of the economy would most influence their voting. B. Approximately 56% of all Louisiana voters thought the state of the economy would most influence their voting. C. Exactly 56% of Louisiana voters would vote for the candidate with the best plan to improve the economy. D. Approximately 56% of Louisiana voters would vote for the candidate with the best plan to improve the economy. Correct answer: B Difficulty level: 3 11. A bottling company sells bottles of water. A random sample of 50 water bottles found that the bottles contained, on average, 0.96 liters of water, and the estimate had a margin of error of 0.08 liters at the 95% confidence level. Which of the following is a reasonable claim to make based on this sample? A. The company always fills its water bottles with less than 1 liter of water. B. The company usually fills its water bottles with between 0.96 liters and 1.04 liters of water. C. The company always fills its water bottles with between 0.88 liters and 1.04 liters of water. D. It is plausible that, on average, the company fills its water bottles with 1 or more liters of water. Correct answer: D Difficulty level: 4 12. An archaeologist uses an accelerator mass spectrometer to find the age of a buried branch. At the 68% confidence level, the spectrometer estimates that the branch was 10,000 years old with a margin of error of 200 years. Which of the following could the spectrometer estimate as the age of the branch at the 95% confidence level? A. 9,500 years old, with a margin of error of 500 years B. 10,000 years old, with a margin of error of 400 years C. 9,500 years old, with a margin of error of 50 years D. 10,000 years old, with a margin of error of 40 years Correct answer: B Difficulty level: 4 13. A random sample of 500 residents of a town included 173 residents who primarily spoke a language other than English at home, with a margin of error of 25 residents and a confidence level of 98%. If the town has 25,000 residents, how many residents primarily speak a language other than English at home, with the 98% confidence level? A. 7,400 to 9,900 residents B. 8,625 to 8,675 residents C. 24,475 to 24,525 residents D. 23,250 to 25,750 residents Correct answer: A Difficulty level: 4 14. In the National Health and Nutrition Examination Survey, 80.5% of the participants had healthy levels of high-density lipoprotein (HDL) cholesterol, the estimate has a margin of error of 1.5% at a confidence level of 95%. The participants were a random sample of United States (US) residents. If the US population at the time of the study was 316 million people, what is the estimate at a 95% confidence level of the number of people in the US who had healthy levels of HDL cholesterol? A. 237 million to 246 million people B. 245million to 264 million people C. 250 million to 259 million people D. 254 million to 300 million people Correct answer: C Difficulty level: 4 15. A university had 150 students registered for an introductory sociology class. The students were randomly assigned to either a section taught with case studies or with lectures. Both sections took the same final exam. Both margins of error are at a 90% confidence level. Which of the following conclusions is the most reasonable regarding the sociology class? A. The university should only offer the lecture teaching method, because students in that section had a higher final exam average. B. The university should not offer either teaching method, case studies or lectures, because neither section achieved the target 90% average. C. The university should only offer the lecture teaching method, because the final exam average plus the margin of error achieved the target 90%. D. The university does not have strong evidence to indicate which teaching method is more effective. Correct answer: D Difficulty level: 4