Exam 7: Sampling Distributions

Assume that house prices in a neighborhood are normally distributed with a standard deviation of $20,000.A random sample of 16 observations is taken.What is the probability that the sample mean differs from the population mean by more than $5,000?

TABLE 7-5 According to an article,19% of the entire population in a developing country has high-speed access to the Internet.Random sample sizes of 200 are selected from the country's population. -Referring to Table 7-5,the population mean of all the sample proportions is ________.

TABLE 7-4 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random sample sizes of 50 are selected. -Referring to Table 7-4,90% of the samples will have less than what percentage of customers who will make a purchase after visiting the website?

TABLE 7-6 Online customer service is a key element to successful online retailing.According to a marketing survey,37.5% of online customers take advantage of the online customer service.Random samples of 200 customers are selected. -Referring to Table 7-6,90% of the samples proportions symmetrically around the population proportion will have between ________% and ________% of the customers who take advantage of online customer service.

TABLE 7-2 The mean selling price of new homes in a small town over a year was $115,000.The population standard deviation was $25,000.A random sample of 100 new home sales from this city was taken. -Referring to Table 7-2,what is the probability that the sample mean selling price was between $113,000 and $117,000?

True or False: The mean of the sampling distribution of a sample proportion is the population proportion,π.

TABLE 7-4 According to a survey,only 15% of customers who visited the website of a major retail store made a purchase.Random sample sizes of 50 are selected. -Referring to Table 7-4,what proportion of the samples will have between 20% and 30% of customers who will make a purchase after visiting the website?