Exam 7: Sampling Distributions

Instruction 7.6 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 7.6,_________ % of the samples are likely to have less than 37.5% who take advantage of online customer service.

The mean of the sampling distribution of a sample proportion is the population proportion,π.

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 amount of pyridoxine (in grams)per multiple vitamin is normally distributed with $\mu$ = 110 grams and $\sigma$ = 25 grams.A sample of 25 vitamins is to be selected. -What is the probability that the sample mean will be between 100 and 120 grams?

The standard error of the mean is also known as the standard deviation of the sampling distribution of the sample mean.

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,95% of all sample means will fall between what two values?

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 1078.2 and 1079.4 grams is _____

Suppose the ages of students in first-year Statistics 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 statements about the sampling distribution of the sample mean age is incorrect?

The amount of pyridoxine (in grams)per multiple vitamin is normally distributed with $\mu$ = 110 grams and $\sigma$ = 25 grams.A sample of 25 vitamins is to be selected. -So,95% of all sample means will be greater than how many grams?

The _________ states that,as the sample size gets large enough,the sampling distribution of the mean is approximately normally distributed.

Instruction 7.5 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 7.5,among all the random samples of size 200,_________ % will have between 14% and 24% who have high-speed access to the Internet.

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.What was the standard error for the sample mean salary?

The distribution of the number of loaves of bread sold per day by a large bakery over the past 5 years has a mean of 7,750 and a standard deviation of 145 loaves.Suppose a random sample of n = 40 days has been selected.What is the approximate probability that the average number of loaves sold in the sampled days exceeds 7,895 loaves?

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,without doing the calculations,state in which of the following ranges the sample mean selling price is most likely to lie?

The standard error of the mean for a sample of 100 is 30.What is the standard deviation?

In inferential statistics,the sampling distribution of the sample mean represents _________.

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?

Instruction 7.5 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 7.5,the standard error of all the sample proportions is _________

Instruction 7.5 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 7.5,among all the random samples of size 200,_________ % will have between 9% and 29% who have high-speed access to the Internet.

Suppose μ = 80 and σ = 20 for a population.In a sample where n = 100 is randomly taken,95% of all possible sample means will fall above 76.71.