Exam 7: Sampling Distributions

Instruction 7-2 The mean selling price of new homes in a country town over a year was $115,000.The population standard deviation was $25,000.A random sample of 100 new home sales from this town was taken. -Referring to Instruction 7-2,what is the probability that the sample mean selling price was between $114,000 and $116,000?

Which of the following is NOT a reason for the need for sampling?

Instruction 7-4 According to a survey,only 15% of customers who visited the web site of a major retail store made a purchase.Random samples of size 50 are selected. -Referring to Instruction 7-4,what is the probability that a random sample of 50 will have at least 30% of customers who will make a purchase after visiting the web site?

Instruction 7-6 According to an article,19% of the entire Australian population have high-speed access to the Internet.Random samples of size 200 are selected from the Australian population. -Referring to Instruction 7-6,among all the random samples of size 200,90% will have more than ________% who have high-speed access to the Internet.

The owner of a fish market has an assistant who has determined that the weights of rainbow trout are normally distributed,with mean of 3.2 kilograms and standard deviation of 0.8 kilogram.What percentage of samples of 4 fish will have sample means between 3.0 and 4.0 kilograms?

Instruction 7-6 According to an article,19% of the entire Australian population have high-speed access to the Internet.Random samples of size 200 are selected from the Australian population. -Referring to Instruction 7-6,among all the random samples of size 200,________% will have less than 20% who have high-speed access to the Internet.

As the size of the sample is increased,the standard deviation of the sampling distribution of the sample mean for a normally distributed population will stay the same.

The only way one can eliminate sampling error is to take the whole population as the sample.

Suppose a sample of n = 50 items is drawn from a population of manufactured products and the weight,X,of each item is recorded.Prior experience has shown that the weight has a probability distribution with μ = 180 grams and σ = 75 grams.Which of the following is true about the sampling distribution of the sample mean if a sample size of 15 is selected?

The amount of pyridoxine (in grams)per multiple vitamin is normally distributed with μ = 110 grams and σ = 25 grams.A sample of 25 vitamins is to be selected.What is the probability that the sample mean will be less than 100 grams?

The Central Limit Theorem ensures that the sampling distribution of the sample mean approaches normal as the sample size increases.

If you randomly select a student from the first row of a business statistics class and then every other 5 students thereafter until you get a sample of 20 students,this is an example of a convenience sample.

Suppose the ages of students in first-year Statistics 101 follow a skewed-right distribution with a mean of 23 years and a standard deviation of 3 years.If we randomly sampled 100 students,which of the following is true about the sampling distribution of the sample mean?

Which of the following is NOT a source of measurement error?

When the results of non-probability samples are used to make conclusions about the entire population,ethical issues are also likely to arise.

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

A statistic calculated from a sample is used to estimate the corresponding

Australian football salaries averaged $150,000 with a standard deviation of $80,000 in a recent year.Suppose a sample of 100 football players was taken.Find the approximate probability that the average salary of the 100 players exceeded $100,000.

Assume that house prices in a neighbourhood are normally distributed with standard deviation $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?

To use the normal distribution to approximate the binomial distribution,we need ________ and ________ to be at least 5.