A national organization has been working with electric companies throughout the US to find sites for large windmills to generate electric power.  Wind speeds must average more than 21 miles per hour (mph) for a site to be acceptable.  Recently, the organization conducted tests at a particular site where windmills are under construction.  Based on a sample of n = 40 wind speed recordings (taken at random intervals) at the site, the wind speeds averaged 23 mph with a standard deviation of 3.9 mph.  To determine whether the site meets the organization’s requirements, they want to test:    Ho:  μ = 21 mph    Ha:  μ > 21 mph using a significance level (α) = 0.01. Should the organization reject or not reject the null hypothesis?  Why or why not?

Suppose that a random sample of 256 measurements is selected from a population with a mean of 50 lb and a variance of 16 lb2.  What is the mean and standard deviation of the sampling distribution of the sample mean?

Which of the following probabilities for the sample points A, B, and C could be true if A, B, and C are the only sample points in an experiment?

For small samples (n < 30), the sampling distribution of the sample mean depends on the particular form of the relative frequency distribution of the population being sampled.

According to a study conducted at a university, many adults have experienced lingering “fright” effects from a scary movie or TV show they saw as a teenager.  In a survey of 150 college students, 39 said that they still experience “residual anxiety” from a scary movie or TV show. Construct a 95% confidence interval to estimate the true population proportion of college students who experience “residual anxiety” from a scary movie or TV show.

An experiment is conducted to compare the starting salaries of male and female college graduates who find jobs.  Pairs are formed by choosing a male and a female with the same major and similar grade point averages.  Suppose a random sample of 10 pairs is formed in this manner and the starting annual salary of each person is recorded.  The differences within the pairs are obtained by subtracting the female salary from the male salary. The following results are obtained:      Mean difference in starting salaries = $400      Standard deviation of the difference in starting salaries = $435 Construct a 95% confidence interval for the true mean difference in starting salaries of the male and female graduates.

Find the standard deviation of a binomial probability distribution with a sample size of n = 20 and a probability of success of 0.40.

It seems reasonable to assume that ovulation rate and litter size in pigs would be positively correlated.  In other words, if a sow releases more eggs (i.e., ova) in a given estrus period, she will probably end up producing more pigs in her litter.  Number of eggs ovulated and litter size for a random sample of 6 sows are as follows: Number of Eggs, X       Number of Pigs Born, Y                14                                  7                15                                  7                16                                  9                17                                 10                17                                 10                17                                  11 Use the deterministic component of the straight-line probabilistic model to obtain the predicted litter size if a sow ovulates 16 eggs.

An animal scientist is interested in determining the proportion of ewes that give birth to twins.  Rather than examine the records for all ewes in the United States, he randomly selects 500 ewes and finds that 220 of them gave birth to twins.  He constructs a 99% large-sample confidence interval to estimate the true population proportion of ewes that give birth to twins.  The correct interpretation of the confidence interval that he derived is:

Suppose that a random sample of 100 measurements is selected from a population with a mean µ = 200 lb and a variance σ2 = 1,600 lb2.  What is the mean and standard deviation of the sampling distribution of the sample mean?