Stats Study Sheet

1. Assume 20% of in all email is spam. A large Internet provider plans on conducting a survey of 900 emails to see what percentage are spam. a. What is the probability they provide rise a proportion greater than 0. 1836? b. If they get a ideal proportion over 24% they are going to shut cut their email server. What is the probability this will happen? 2. A survey is through with(p) to estimate the proportion of U. S. adults who think that cell audio use sequence driving should be illegal. In the survey, 54% of a randomly selected stress of 1025 individuals verbalise that cell phone use while driving should be illegal. a.What is the 90% authorisation detachment for the proportion of adults who think cell phone use should be illegal? 1. A precedent of college students was asked whether they would refurbishment the silver if they found a wallet on the street. Of the 93 women, 84 said yes, and of the 75 men, 53 said yes. Assume that these students represent all college stu dents (Data computer address is from UC Davis and peck be found in the textbook). a. Is there adequacy selective information to predict a sanction breakup for the women? 2. A sample of college students was asked whether they would return the money if they found a wallet on the street.Of the 93 women, 84 said yes, and of the 75 men, 53 said yes. Assume that these students represent all college students (Data source is from UC Davis and discharge be found in the textbook). b. Is there enough data to calculate a confidence musical interval for the women? 3. A CNN/ era poll conducted in the United States October 23-24, 2002, (http//www. pollingreport. com) asked, Do you favor or scar the legalization of marijuana? In the nationwide poll of n = 1007 adults, 34% said that they favored legalization. a.Find the margin of error for a 96% confidence interval. 3. A medical researcher wants to study whether literal contraceptives are jibe with gritty blood pressure. A sample of 500 women development oral contraceptives showed 15% had last blood pressure A sample of cd women not using oral contraceptives showed 10% had high blood pressure. a. What is the 92% confidence interval for the difference in the deuce proportions? (using not using) 4. A medical researcher wants to study whether oral contraceptives are correlated with high blood pressure.A sample of 500 women using oral contraceptives showed 15% had high blood pressure A sample of 400 women not using oral contraceptives showed 10% had high blood pressure. b. What is the 92% confidence interval for the difference in the two proportions? (using not using) b. If the magazine had wanted to get a margin of error of only 1%, at least how many adults should they have interviewed? 1. University of Wyoming policy states that you should spend 6 hours a calendar week on planning. To find out how close our class is we randomly sample 100 students from class and ask, How many hours do you spend on homework e ach week? The repute for the 100 responses is 3. 6 hours with a old-hat dispute of 0. 7 hours (sample statistic). Find a 95% confidence interval for the true average. * We use 80 degrees of exemption, because (1) t-table does not have t-values for 99 degrees of freedom and also because using 100 degrees of freedom is too liberal. The reason is that we can never say we have more data than you really do OK to say you have less. * We use t-table and not z-table because our standard diversion has been computed from sample values. 7.The center for malady control wants to know the average life span of an ebola virus. Studies of similar types of viruses counsel the standard digression will be 2. 55 days (population tilt use z-table), but they want a 99% confidence interval for the true average lifespan, and they want that confidence interval to have a width of 0. 5 days. How many ebola viruses do they need to sample? We can use z-table rather of t-table because the standard devia tion comes from the population. We can use z-table instead of t-table because the standard deviation comes from the population. 7.The center for disease control wants to know the average life span of an ebola virus. Studies of similar types of viruses suggest the standard deviation will be 2. 55 days (population parameter use z-table), but they want a 99% confidence interval for the true average lifespan, and they want that confidence interval to have a width of 0. 5 days. How many ebola viruses do they need to sample? We can use z-table instead of t-table because the standard deviation comes from the population. We can use z-table instead of t-table because the standard deviation comes from the population. 9.Example 11. 12 (p. 428) studies hangover symptoms in college students (Slutske et al. , 2003). The students answered questions about alcoholic beverage use and hangovers, including a count of how many out of a inclining of 13 possible hangover symptoms that they had experie nced in the past year. For the 470 men, the intend number of symptoms was 5. 3 for the 755 women, it was 5. 1. The standard deviation was 3. 4 for each of the two samples. a. Find a 95% confidence interval for the difference in population means. 9. Example 11. 12 (p. 428) studies hangover symptoms in college students (Slutske et al. 2003). The students answered questions about alcohol use and hangovers, including a count of how many out of a rock of 13 possible hangover symptoms that they had experienced in the past year. For the 470 men, the mean number of symptoms was 5. 3 for the 755 women, it was 5. 1. The standard deviation was 3. 4 for each of the two samples. a. Find a 95% confidence interval for the difference in population means. 3. In each part, use the information given to calculate the margin of error. a. A sample of n = 81 women has standard deviation 2. 7 inches. Confidence90%