Exam 7: Sampling Distributions

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

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 more than 30% who have high-speed access to the Internet.

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,what is the probability that the sample mean lifetime is more than 1,550 hours?

Coverage error can become an ethical issue if a particular group is intentionally excluded from the frame.

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

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 7-7,95% of the samples proportions symmetrically around the population proportion will have between ________% and ________% of the customers who take advantage of online customer service.

The amount of time required for an oil and filter change on a car is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes.A random sample of 16 cars is selected.What would you expect the standard error of the mean to be?

The amount of time required for an oil and filter change on a car is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes.A random sample of 16 cars is selected.What is the probability that the sample mean is between 45 and 52 minutes?

A manufacturer of power tools claims that the average 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 mean of the sampling distribution of the sample mean is ________ minutes.

A convenience sample is a type of probability sample.

Instruction 7-1 Times spent studying by students in the week before final exams follow 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 Instruction 7-1,what is the probability that the sample mean exceeds the population mean by more than 2 hours?

A study at a university in New South Wales reveals that,historically,45% of their students are minority students.The expected percentage of minority students in their next batch of first-year students is ________.

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.If a sample of 16 fish is taken,what would the standard error of the mean weight equal?

The amount of time required for an oil and filter change on a car is normally distributed with a mean of 45 minutes and a standard deviation of 10 minutes.A random sample of 16 cars is selected.So,90% of the sample means will be greater than what value?

To gather opinions on the efficacy of Australian foreign policies,a sample of 50 faculty members is selected from the pool of university lecturers who have taught political science at the post-graduate level.This is an example of a judgement sample.

The question: "How much did you make last year rounded to the nearest hundreds of dollars?" will most likely result in measurement error.

When participants are allowed to self-select into the sample,you have a non-probability 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 between 1018.9 and 1022.3 grams is ________.

As the sample size increases,the standard error of the mean increases.

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