RVCC Statistics I Homework A random sample of 28 students' final exam scores in Statistics I, revealed a mean of 63.39 with a standard deviation of 25. 17. It is assumed that the grades follow a normal distribution. The teacher believes that on interval. the average his students' final exams are lower than C (70%). Construct and interpret a 90% confidence 10. According to Communications Industry Forecast and Reports, the average person spent 5 hours a day on internet in 2019. In 2020, a random sample of 20 people gave the following number of hours spent on internet: 9.1 4.6 5.4 3.7 5.2 6.9 1.7 6.1 6.1 1.9 7.6 5.5 9 3.9 2.5 2.4 4.7 4.1 3.7 Construct and interpret a 95% confidence interval for the population mean. 1 1. Researchers studies various characteristics of political prisoners from the former East Germany and present their findings in a journal article. According to the article, the mean duration of imprisonment for 32 patients with chronic PTSD was 33. 4 months. Assuming a population standard deviation of 42 months, calculate and interpret a 95% confidence interval for the mean duration of imprisonment of all east German political prisoners with chronic PTSD. 12. The Rolling Stones, a rock group formed in the 1960s, have toured extensively in support of new albums. Data has been collected on the earnings from the Stone's North American tours. For 30 randomly selected Rolling Stones concerts, the mean gross earning is $2.27 million with a standard deviation of $0.5 million. Calculate and interpret a 99% confidence interval for the mean gross earning of all Rolling Stones concerts in North America. 13. A decade ago, a sample of the ages of 16 millionaires in the United States was obtained. The mean and standard deviation were 58.55 years and 7.99 years, respectively. Calculate and interpret a 95% confidence interval for the average age of all millionaires in in the U.S. A. Assume the population of millionaires is normally distributed. 14. Researchers studied how people adjust to prison life. A sample of 712 federally sentenced adult mail prisoners had an average sentence of 9.15 years. Assume that, for federally sentenced adult male prisoners, the population standard deviation of sentence length is 17. 2 years. Calculate and interpret a 95% confidence interval for the mean sentence length of all federally sentenced adult male prisoners. Page 3