Exam 7: Sampling and Sampling Distributions

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 population mean of all possible sample proportions is ________.

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,________ % of the samples are likely to have less than 37.5% who take advantage of online customer service.

Which of the following is true about the sampling distribution of the sample mean?

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 200,90 % will have more than ________ % who have high-speed access to the Internet.

For air travelers,one of the biggest complaints is of the waiting time between when the airplane taxis away from the terminal until the flight takes off.This waiting time is known to have a right skewed distribution with a mean of 10 minutes and a standard deviation of 8 minutes.Suppose 100 flights have been randomly sampled.Describe the sampling distribution of the mean waiting time between when the airplane taxis away from the terminal until the flight takes off for these 100 flights.

TABLE 7-4 The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours.A random sample of 64 of these light bulbs is taken. -Referring to Table 7-4,the probability is 0.20 that the sample mean lifetime differs from the population mean lifetime by at least how many hours?

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 is more than 3 hours below the population mean?

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 ________.

The question "How many times have you abused your spouse in the last 6 months?" will most likely result in nonresponse error.

A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line table saw is 80 minutes with a standard deviation of 40 minutes.Suppose a random sample of 64 purchasers of this table saw is taken.The probability that the sample mean will be greater than 88 minutes is ________.

An electronic appliance chain gathered customer opinions on their services using the customer feedback forms that are attached to the product registration forms.This is an example of a convenience sample.

Sales prices of baseball cards from the 1960s are known to possess a right skewed distribution with a mean sale price of $5.25 and a standard deviation of $2.80.Suppose a random sample of 100 cards from the 1960s is selected.Describe the sampling distribution for the sample mean sale price of the selected cards.

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 sampling distribution of the sample mean will be approximately normal only if the population sampled is normal.

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.

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 more than $110,000?

The amount of tea leaves in a can from a particular production line is normally distributed with μ = 110 grams and σ = 25 grams.A sample of 25 cans is to be selected.So,95% of all sample means will be greater than how many grams?

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 ________.