Exam 7: Sampling Distributions

Instruction 7-5 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. -Referring to Instruction 7-5,which of the following questions in the survey will NOT likely induce a measurement error?

If the amount of petrol purchased per car at a large petrol station has a population mean of $15 and a population standard deviation of $4 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.

A sampling distribution is a probability distribution for a statistic.

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,the requirements for using a normal distribution to approximate a binomial distribution is fulfilled.

Instruction 7-3 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 Instruction 7-3,the probability is 0.15 that the sample mean lifetime is more than how many hours?

A sample is selected by including everybody who sits in the first row of a business statistics class.This is an example of a cluster sample.

The amount of bleach a machine pours into bottles has a mean of 1080 grams with a standard deviation of 4.5 grams.Suppose we take a random sample of 36 bottles filled by this machine.The probability that the mean of the sample is less than 1080.9 is ________.

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

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?

Instruction 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 Instruction 7-7,________% of the samples are likely to have less than 37.5% who take advantage of online customer service.

In inferential statistics,the standard error of the sample mean assesses the uncertainty or error of estimation.

Suppose μ = 50 and σ² = 100 for a population.In a sample where n = 100 is randomly taken,90% of all possible sample means will fall between 49 and 51.

The sample mean is an unbiased estimate of the population mean.

For a population frame containing N = 1,007 individuals,what code number should you assign to the first person on the list in order to use a table of random numbers?

A study at a university in New South Wales reveals that,historically,45% of their students are minority students.If a random sample of size 75 is selected,the probability is ________ that more than half of the students in the sample will be minority students.

Measurement error will become an ethical issue when the findings are presented without reference to sample size and margin of error.

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

Which of the following statements about the sampling distribution of the sample mean is incorrect?

The Central Limit Theorem is important in statistics because

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,the standard deviation of all the sample proportions of customers who will make a purchase after visiting the web site is ________.