Exam 7: Sampling and Sampling Distributions

The College Student Journal (December 1992)investigated differences in traditional and nontraditional students,where nontraditional students are defined as 25 years or older and working.Based on the study results,we can assume the population mean and standard deviation for the GPA of nontraditional students is µ = 3.5 and $\sigma$ = 0.5.Suppose a random sample of 100 nontraditional students is selected and each student's GPA is calculated.Find the interval that contains 95.44% of the sample means for nontraditional students.

If the sample size n is infinitely large,then is an unbiased estimator of. .

As the sample size increases the variability of the sampling distribution of the mean ______________.

The ___________ is a minimum-variance unbiased point estimate of the mean of a normally distributed population.

If we wish to estimate a population parameter by using a sample statistic,we are using _____.

A random sample of size 1,000 is taken from a population where p = .20.Find P ( > .21).

The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.3 inches.What is the probability that average length of a steel sheet from a sample of 9 units is more than 29.95 inches long?

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P ( < 48).

The College Student Journal (December 1992)investigated differences in traditional and nontraditional students,where nontraditional students are defined as 25 years or older and working.Based on the study results,we can assume the population mean and standard deviation for the GPA of nontraditional students is µ = 3.5 and $\sigma$ = 0.5.Suppose a random sample of 100 nontraditional students is selected and each student's GPA is calculated.Calculated

It has been reported that the average time to download the home page from a government website was 0.9 seconds.Suppose that the download times were normally distributed with a standard deviation of 0.3 seconds.If random samples of 36 download times are selected calculate the mean of the sampling distribution of the sampling mean.

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.What is ?

A 'Yes or No' question is _____________.

Find

_____________ occurs when some population elements are excluded from the process of selecting the sample.

Suppose that 60 percent of the voters in a particular region support a candidate.Find the probability that a sample of 1,000 voters would yield a sample proportion in favor of the candidate within 4 percentage points of the actual proportion.

The mean of the sampling distribution of the sample proportion is equal to _____ when the sample size is sufficiently large.

A random sample of size 36 is taken from a population with mean 50 and standard deviation 5.Find P ( > 49).

An unbiased estimate of is _____.

A PGA (Professional Golf Association)tournament organizer is attempting to determine whether hole (pin)placement has a significant impact on the average number of strokes for the 13^th hole on a given golf course.Historically,the pin has been placed in the front right corner of the green,and the historical mean number of strokes for the hole has been 4.25,with a standard deviation of 1.6 strokes.On a particular day during the most recent golf tournament,the organizer placed the hole (pin)in the back left corner of the green.64 golfers played the hole with the new placement on that day.Determine the probability of the sample average number of strokes exceeding 4.75.

In a manufacturing process a machine produces bolts that have an average length of 3 inches with a variance of .03.If we randomly select three bolts from this process: What is the standard deviation of the sampling distribution of the sample mean?