A random sample of 189 students were asked how many songs were in their digital music library and what fraction of them were legally purchased. Overall, they reported having a total of 117,738 songs, of which 21.6% were legal. The music industry would like a good estimate of the percentage of songs in students' digital libraries that are legal.
a) |
What is the parameter being estimated? What is the population? What is the sample size? |
b) |
Construct a 99% confidence interval for the fraction of legal digital music, if you can. If not, explain the problem. |
A random sample of 189 students were asked how many songs were in their digital music library and what fraction of them...
a simple random sample of 511 adults were asked if they agreed
medical
A simple random sample of 511 adults were asked if they agreed medical marijuana should be legally available. Based on the 511 responses, 64% of respondents voted yes. a) Identify the population b) Identify the sample c) is the sample representative of the population? If no, what sampling method would best represent the population? d) 64% of respondents voted yes, find the probability of randomly selecting 10...
4. A survey asked a random sample of 363 first-year students how many hours they studied during a particular week. The mean was 15.3 hours. Suppose we know that the population standard deviation is 8.5 hours. Construct a 90%, 95% and 99% confidence interval for the mean study time of all first year students at this university. Interpret the 90% confidence interval.
A sample of 250 students who were taking online courses were asked to describe their overall impression of online learning on a scale of 1-7 with 7 representing the most favorable impression. The average score was 4.98 and the standard deviation was 0.87. Construct a 90% confidence interval for the mean score. Round your final answers to 3 decimal places. The 90% confidence interval for the mean score is: ( , )
31 stats students were asked how long it took them to finish the midterm exam. The sample mean was found to be 192 minutes and the sample standard deviation was 7 minutes. Create a 99% confidence interval for the population mean.
A random sample of students were asked whether they were satisfied with their school's lunch menu. The resulting confidence interval for the proportion of students who are satisfied is (0.33,0.51). What is the margin of error?
A random sample of 13 students were asked how long it took them to complete a certain exam. The mean length of time was 105.5 minutes, with a standard deviation of 66.7 minutes. Find the lower bound of the 90% confidence interval for the true mean length of time it would take for all students to complete the exam. Round to one decimal place (for example: 108.1). Write only a number as your answer. Do not write any units.
A random sample of 240 students were asked “Do you buy your books from the UP bookstore?” and 42% said “yes”. Construct a 90% confidence interval for the true population proportion (p) of students who buy their books at the UP bookstore. Interpret your answer:
Question 5 (13 points) A random sample of 20 NAU students were asked how many hours of television they watch each week. The following is StatKey output for this data. Bootstrap Dotplot of Mean 400 Left Tail Two-TallRight Tail 350 samples - 10000 mean 5.453 std. error -0.511 Original Samp n-20, mean - 5.45 median-5, stdey - 15 10 5 300 0 250 2 4 200 150 0.025 0.950 0.025 100 Bootstrap Sam Show Data Table n-20, mean - 5.05...
A random sample of university students were asked whether they participate in varsity athletics and how many times they had used marijuana in the last ten days. If the necessary conditions are met, which of the following methods would be most appropriate to test for an association between the whether or not a student participates in varsity athletics and the frequency of marijuana use? A) One sample t-test B) Paired t-test C) Two sample t-test for difference in means D)...
Sleeping outlier: A simple random sample of eight college freshmen were asked how many hours of sleep they typically got per night. The results were 24 6 8.5 8 8.5 7.5 6.5 9 Send data to Excel Notice that one joker said that he sleeps 24 a day. Part: 0/ 3 Part 1 of 3 (a) The data contain an outlier that is clearly a mistake. Eliminate the outlier, then construct a 90 % confidence interval for the mean amount...