If the variation within sample means is large relative to the variation between the samples, it indicates that there is a real difference between the population means.

Suppose x has a binomial probability distribution with n = 200 and p = 0.70.  Use the normal approximation to the binomial to find P (X > 150).

The American Journal of Orthopsychiatry published an article on the prevalence of homelessness in the United States.  A sample of 500 adults was asked to respond to the question:  “Was there ever a time in your life when you did not have a place to live”?  A total of 30 adults in the sample answered yes to this question. Is the sample size in this problem large enough for large-sample confidence interval procedures to be valid?

Suppose x has a binomial probability distribution with n = 200 and p = 0.60.  Use the normal approximation to the binomial to find P (X 

Suppose that a veterinarian has received permission from the owners of 50 dogs to use their dogs in an experiment involving a new drug for cancer treatment.  The vet decides to use 5 of the 50 available dogs for a small preliminary experiment before conducting a larger study.  The vet arbitrarily begins at row 8 column 1 of the random number table and goes from left to right across the row.  Which one of the following is the correct random sample of 5 dogs? For your convenience, here are rows 8 and 9 of the random number table:       Column       Row 1 2 3 4 5 6 8 96301 91977 05463 07972 18876 20922 9 89579 14342 63661 10281 17453 18103

A plant scientist wants to determine the average yield (in bushels per acre) of brand X corn in Ohio.  Five thousand Ohio corn fields are planted using brand X.  The plant scientist is able to obtain data for the yields of 500 of these 5,000 fields.  The average yield of these 500 fields planted to brand X is 175 bushels per acre.  What is the population of interest to the plant scientist?

Assume that the mean score on an IQ test is a 100 and that the standard deviation of the scores is 15.  The highest IQ score among the people taking the test was a 160.  Calculate the z-score for the person with the highest score of 160.  Based on the z-score, is this score of 160 an outlier?  Why or why not?

A state energy agency mailed questionnaires on energy conservation to 1,000 homeowners in Columbus.  Suppose an experiment consists of randomly selecting one of the returned questionnaires.  Consider the events:    Event A:  the home is constructed of brick    Event B:  the home is more than 30 years old    Event C:  the home is heated with oil A home that is constructed of brick and is more than 30 years old would be represented by which one of the following?

The mean score on an IQ test is a 100 and the standard deviation of the scores is 15.  If the distribution of IQ scores is symmetric and mound-shaped, what percentage of the scores would be expected to fall between 70 and 130?

In seeking a free agent NFL running back, a general manager is looking for a player with a high mean for yards gained per carry and a small standard deviation.  Suppose the GM wishes to compare the mean yards gained per carry for two free agents based on independent random samples of their yards gained per carry.  Data from last year’s pro football season indicate that σ1 and σ2 are both equal to approximately 5 yards.  If the GM wants to estimate the difference in means for yards gained per carry by the two running backs correct to within 1 yard with a confidence level of 0.90, how many carries would have to be observed for each of the two players?  Assume equal sample sizes.