Stats Study Sheet

1. contain 20% of every telecommunicate is spam. A large earnings provider plans on conducting a batch of 900 emails to see what percentage ar spam. a. What is the prospect they will turn a similarity greater than 0. 1836? b. If they get a render ratio over 24% they are going to shut down their email server. What is the probability this will happen? 2. A survey is done to estimate the proportion of U. S. adults who succumb that cell phone enjoyment while driving should be illegal. In the survey, 54% of a at random selected savour of 1025 individuals express that cell phone social function while driving should be illegal. a.What is the 90% say-so time musical interval for the proportion of adults who think cell phone social occasion should be illegal? 1. A judge of college students was asked whether they would return the money if they found a pocketbook on the street. Of the 93 women, 84 state yes, and of the 75 men, 53 tell yes. Assume that these students rep resent all college students (Data rootage is from UC Davis and post be found in the textbook). a. Is at that place enough data to describe a assumption interval 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 cigaret be found in the textbook). b. Is there enough data to calculate a self-confidence interval for the women? 3. A CNN/Time poll conducted in the unite States October 23-24, 2002, (http//www. pollingreport. com) asked, Do you favor or gibe the legalization of marijuana? In the across the nation poll of n = blow7 adults, 34% said that they favored legalization. a.Find the margin of error for a 96% confidence interval. 3. A medical examination researcher demands to guide whether spoken contraceptives are correlated with laid-b ack kind pull. A sample of 500 women using oral contraceptives showed 15% had towering blood pressure A sample of cd women non using oral contraceptives showed 10% had high blood pressure. a. What is the 92% confidence interval for the difference in the 2 proportions? (using non 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 deuce proportions? (using not using) b. If the magazine had wanted to get a margin of error of only 1%, at least how umpteen adults should they read interviewed? 1. University of Wyoming policy states that you should spend 6 hours a week on readiness. To mystify let out how close our class is we randomly sample vitamin C students from class and ask , How umteen hours do you spend on homework to each one week? The mean for the 100 responses is 3. 6 hours with a measuring stick recreation of 0. 7 hours (sample statistic). Find a 95% confidence interval for the true modal(a). * We enforce 80 degrees of freedom, beca intention (1) t-table does not have t-values for 99 degrees of freedom and also beca do using 100 degrees of freedom is too liberal. The reason is that we cease 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 banner divagation has been computed from sample values. 7.The place for disease retard wants to know the honest life intersect of an ebola virus. Studies of similar types of viruses purpose the timeworn aberration will be 2. 55 age ( creation 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 largeness of 0. 5 days. How more ebola viru ses do they inquire to sample? We can use z-table rather 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. 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 legion(predicate) 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 hubbub symptoms in college students (Slutske et al. , 2003). The students answered questions about intoxicant use and hangovers, inc luding a count of how many out of a list of 13 achievable hangover symptoms that they had experienced in the knightly 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. 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 list 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 discipline given to calculate the margin of error. a. A sample of n = 81 women has standard deviation 2. 7 inches. Confid ence90%