Exam 7: Sampling and Sampling Distributions

TABLE 7-2 The time spent studying by students in the week before final exams follows a normal distribution with a standard deviation of 8 hours. A random sample of 4 students was taken in order to estimate the mean study time for the population of all students. -Referring to Table 7-2, what is the probability that the sample mean exceeds the population mean by more than 2 hours?

The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a DVD player made by the company over the past 12 months are satisfied with their products. Which of the following will be a good frame for drawing a sample?

TABLE 7-6 According to an article, 19% of the entire population in a developing country have high-speed access to the Internet. Random samples of size 200 are selected from the country's population. -Referring to Table 7-6, among all the random samples of size 200, ________ % will have between 9% and 29% who have high-speed access to the Internet.

The question "Is your household income last year somewhere between $50,000 and $100,000?" will most likely result in coverage error.

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -Referring to Table 7-5, the mean of all the sample proportions of customers who will make a purchase after visiting the website is ________.

To gather opinions on the efficacy of U.S. foreign policies, a sample of 50 faculty members is selected from the pool of university professors who have taught political science at the graduate level. This is an example of a judgment sample.

The amount of bleach a machine pours into bottles has a mean of 36 oz. with a standard deviation of 0.15 oz. Suppose we take a random sample of 36 bottles filled by this machine. The probability that the mean of the sample is less than 36.03 is ________.

________ results from the failure to collect data on all subjects in the sample.

TABLE 7-5 According to a survey, only 15% of customers who visited the website of a major retail store made a purchase. Random samples of size 50 are selected. -Referring to Table 7-5, 90% of the samples will have less than what percentage of customers who will make a purchase after visiting the website?

TABLE 7-7 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 7-7, the standard error of all possible sample proportions is ________.

The Central Limit Theorem is considered powerful in statistics because it works for any population distribution provided the sample size is sufficiently large and the population mean and standard deviation are known.

A company selling apparel online sends out emails every Monday to all its customers who made a purchase. This is an example of a

Suppose μ = 80 and σ = 20 for a population. In a sample where n = 100 is randomly taken, 95% of all possible sample means will fall above 76.71.

The amount of time it takes to complete an examination has a left skewed distribution with a mean of 65 minutes and a standard deviation of 8 minutes. If 64 students were randomly sampled, the probability that the sample mean of the sampled students exceeds 71 minutes is approximately 0.

Suppose μ = 50 and σ = 10 for a population. In a sample where n = 100 is randomly taken, 95% of all possible sample means will fall between 48.04 and 51.96.

TABLE 7-3 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 7-3, what is the probability that the sample mean selling price was between $113,000 and $117,000?

The amount of bleach a machine pours into bottles has a mean of 36 oz. with a standard deviation of 0.15 oz. Suppose we take a random sample of 36 bottles filled by this machine. The probability that the mean of the sample exceeds 36.01 oz. is ________.

If a simple random sample is chosen with replacement, each individual has the same chance of selection on every selection.

To find out the potential impact of a new zoning law on a neighborhood, the legislators conduct a focus group interview by inviting the members of the housing owners association of that neighborhood. This is an example of a

Measurement error can become an ethical issue when an interviewer purposely guides the responses in a particular direction.