A survey of college students taking the professional exam to be certified as public school teachers shows that 80 percent pass. On a national exam day, 15,000 students take the test. Let X denote the number of students who pass. Find the mean and standard deviation of this Binomial random variable X. O 3000; 2400 3000; 48.99 OO 12,000; 48.99 O 12,000; 2400 50 1.5 points If a person receives a grade that is better than 45% of the population taking a test, but lower than 55% of the population, his/her grade is said to be at which of the following? O 55th percentile O 45 percentile O median O third quartile 51 1.5 points An automobile manufacturer wants to determine what proportion of its customers are dissatisfied with the service received from their local dealer. The manufacturer's manager doesn't have any estimate for the proportion of dissatisfied customers. How many customers should they sample if they want to be correct to within 2% of the actual proportion with a 90% level of confidence? O 1691 O 608 609 17 O 1692 52 1.5 points Which ONE of the following sampling distributions is approximately normal? O p distribution with p = .90 and sample of size 30 O x distribution, with samples of size 28, from a non-normal population O x distribution, with samples of size 14, from a population of unknown shape p distribution with p = .40 and sample of size 20