In a recent study of 42 eighth graders, the mean number of hours per week that they played video games was 19.6 with a population standard deviation of 5.8 hours. Compute the 98% confidence interval for μ. Group of answer choices (18.3, 20.9) (19.1, 20.4) (14.1, 23.2) (17.5, 21.7) Flag question: Question 7 Question 7 1 pts A 90% confidence interval for the mean percentage of airline reservations being canceled on the day of the flight is (1.2%, 4.5%). What is the point estimator of the mean percentage of reservations that are canceled on the day of the flight? Group of answer choices 2.85% 3.3% 1.65% 2.25% Flag question: Question 8 Question 8 1 pts The cell phone conversations of a random sample of 50 students has a standard deviation of 9.7 minutes. Find the margin of error, E, using a 90% confidence interval. Group of answer choices 0.32

In a recent study of 42 eighth graders, the mean number of hours per week that they played video games was 19.6 with a population standard deviation of 5.8 hours. Compute the 98% confidence interval for μ. Group of answer choices (18.3, 20.9) (19.1, 20.4) (14.1, 23.2) (17.5, 21.7) Flag question: Question 7 Question 7 1 pts A 90% confidence interval for the mean percentage of airline reservations being canceled on the day of the flight is (1.2%, 4.5%). What is the point estimator of the mean percentage of reservations that are canceled on the day of the flight? Group of answer choices 2.85% 3.3% 1.65% 2.25% Flag question: Question 8 Question 8 1 pts The cell phone conversations of a random sample of 50 students has a standard deviation of 9.7 minutes. Find the margin of error, E, using a 90% confidence interval. Group of answer choices 0.32 2.26 1.23 1.37 Flag question: Question 9 Question 9 1 pts Determine the sample size needed to estimate μ for the given situation E = 4, σ = 35, (1 - α) = 0.90 Group of answer choices 4 295 207 208 Flag question: Question 10 Question 10 1 pts Suppose a 99% confidence interval for μ turns out to be (1000, 2100). If this interval was based on a sample of size n = 26, explain what assumptions are necessary for this interval to be valid. Group of answer choices The population must have an approximately normal distribution The sampling distribution of the sample mean must have a normal distribution The population of salaries must have an approximate t distribution. The sampling distribution must be biased with 25 degrees of freedom Flag question: Question 11 Question 11 1 pts Find the critical t-value that corresponds to 90% confidence and n = 15. Group of answer choices 1.761 1.345 2.145 2.624 Flag question: Question 12 Question 12 1 pts Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 25 randomly English majors has a mean test score of 81.5 with a standard deviation of 10.2. Group of answer choices (56.12, 78.34) (87.12, 98.32) (66.35, 69.89) (77.29, 85.71) Flag question: Question 13 Question 13 1 pts Construct a 99% confidence interval for the population mean, μ. Assume the population has a normal distribution. A group of 19 randomly selected employees has a mean age of 22.4 years with a standard deviation of 3.8 years. Group of answer choices (18.7, 24.1) (17.2, 23.6) (16.3, 26.9) (19.9, 24.9) Flag question: Question 14 Question 14 1 pts The grade point averages for 10 randomly selected junior college students are listed below. Assume the grade point averages are normally distributed. Find a 98% confidence interval for the true mean. 2.0 3.2 1.8 2.9 0.9 4.0 3.3 2.9 3.6 0.8 Group of answer choices (1.55, 3.53) (2.12, 3.14) (3.11, 4.35) (0.67, 1.81) Flag question: Question 15 Question 15 1 pts When 500 junior college students were surveyed,120 said that they have previously owned a motorcycle. Find a point estimate for p, the population proportion of students who have previously owned a motorcycle Group of answer choices 0.316 0.240 0.194 0.760 Flag question: Question 16 Question 16 1 pts A survey of 250 households showed 41 owned at least one snow blower. Find a point estimate for p, the population proportion of households that own at least one snow blower. Group of answer choices 0.836 0.141 0.196 0.164 Flag question: Question 17 Question 17 1 pts An article a Florida newspaper reported on the topics that teenagers most want to discuss with their parents. The findings, the results of a poll, showed that 46% would like more discussion about the familyʹs financial situation, 37% would like to talk about school, and 30% would like to talk about religion. These and other percentages were based on a national sampling of 502 teenagers. Estimate the proportion of all teenagers who want more family discussions about school. Use a 95% confidence level. Group of answer choices 0.63 ± 0.002 0.63 ± 0.042 0.37 ± 0.042 0.37 ± 0.002 Flag question: Question 18 Question 18 1 pts A researcher at a major clinic wishes to estimate the proportion of the adult population of the United States that has sleep deprivation. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more than 4%? Group of answer choices 17 2073 849 1037 Flag question: Question 19 Question 19 1 pts A pollster wishes to estimate the number of left-handed scientists. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more than 6%? A previous study indicates that the proportion of left-handed scientists is 9%. Group of answer choices 151 47 124 166 Flag question: Question 20 Question 20 1 pts Many people think that a national lobbyʹs successful fight against gun control legislation is reflecting the will of a minority of Americans. A previous random sample of 4000 citizens yielded 2250 who are in favor of gun control legislation. How many citizens would need to be sampled if a 90% confidence interval was desired to estimate the true proportion to within 3%? Group of answer choices 752 740 782 692