Exam 7: Sampling and Sampling Distributions

For sample sizes greater than 30,the sampling distribution of the mean will be approximately normally distributed

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 less than 20% who have high-speed access to the Internet.

Selection bias occurs more frequently in systematic samples than in simple random samples.

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 between 77 and 89 minutes is ________.

At a computer manufacturing company,the actual size of computer chips is normally distributed with a mean of 1 centimeter and a standard deviation of 0.1 centimeter.A random sample of 12 computer chips is taken.What is the probability that the sample mean will be between 0.99 and 1.01 centimeters?

Which of the following yields a cluster sample?

At a computer manufacturing company,the actual size of computer chips is normally distributed with a mean of 1 centimeter and a standard deviation of 0.1 centimeter.A random sample of 12 computer chips is taken.Above what value do 2.5% of the sample means fall?

Sampling distributions describe the distribution of

If the amount of gasoline purchased per car at a large service station has a population mean of 15 gallons and a population standard deviation of 4 gallons and a random sample of 64 cars is selected,there is approximately a 95.44% chance that the sample mean will be between 14 and 16 gallons.

In a business statistics class students sit randomly without particular preferences.A sample is selected by including everybody who sits in the first row.This is an example of a cluster sample.

The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed,with mean of 3.2 pounds and standard deviation of 0.8 pound.If a sample of 64 fish yields a mean of 3.4 pounds,what is probability of obtaining a sample mean this large or larger?

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.So,the middle 95% of the sample means based on samples of size 64 will be between ________ and ________.

A population frame for a survey contains a listing of 6,179 names.Using a table of random numbers,which of the following code numbers will appear on your list?

As a population becomes large,it is usually better to obtain statistical information from the entire population.

The average score of all pro golfers for a particular course has a mean of 70 and a standard deviation of 3.0.Suppose 36 pro golfers played the course today.Find the probability that the average score of the 36 pro golfers exceeded 71.

The professor of a business statistics class wanted to find out the mean amount of time per week her students spent studying for the class.She divided the students into the left,right and center groups according to the location they sat in the class that day.One of these 3 groups was randomly selected and everyone in the group was asked the mean amount of time per week he/she spent studying for the class.This is an example of a cluster 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. -A study at a college in the west coast reveals that,historically,45% of the students are minority students.If random samples of size 75 are selected,95% of the samples will have more than ________ % of minority students.

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,the middle 70% of all sample means will fall between what two values?

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

The standard deviation of the sampling distribution of a sample proportion is where π is the population proportion.