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We want to test the hypothesis that the mean yield of a particular variety of corn is less than 150 bushels per acre.  Therefore, we obtain the yields of a random sample of 20 corn fields in which this variety was planted. The average yield of the sample of fields was 140 bushels per acre with a standard deviation of 10 bushels per acre.  We want to test:    Ho:  μ = 150 bushels/acre    Ha:  μ < 150 bushels/acre using a significance level (α) = 0.10. Should we reject or not reject the null hypothesis?  Why?

The grades of 8 students on an exam were as follows: Student Grade 1 66 2 70 3 64 4 88 5 74 6 72 7 87 8 79     Find the range for the grades of these 8 students.

Tests for the differences in the mean levels of the main effects in a factorial experiment are relevant only when the factors do not interact.

Find the variance of a binomial probability distribution with a sample size of n = 25 and a probability of success of 0.30.

Sandoz, a pharmaceutical firm, reports that kidney transplant patients who receive the drug cyclosporine have an 80% chance of surviving the first year.  Suppose a hospital performs 4 kidney transplants and all 4 patients receive cyclosporine.  Assuming that one patient’s survival is independent of another’s, what is the probability that at least one of the 4 patients will be alive at the end of 1 year?

An Animal Scientist wants to estimate the average weaning weight of the Angus breed of beef cattle.  Therefore, he selects a random sample of 100 Angus calves and weighs them on the day they are weaned from their mothers.  The sample mean for these 100 calves is 500 lb and the sample standard deviation is 40 lb.  What is the point estimate of the mean of the entire population of all Angus calves?

The Kimberly Clark Corporation wants to determine how many tissues a box of Kleenex should contain.  Researchers determine that 60 is the average number of tissues used by a typical person during a cold.  Suppose a random sample of 100 Kleenex users yielded a sample mean of 56 tissues and a sample standard deviation of 10 tissues used during a typical cold.  Kimberly Clark wants to test:    Ho:  μ = 60 tissues    Ha:  μ < 60 tissues using a significance level (α) = 0.05. What is the correct value of the test statistic that should be used to test the null hypothesis?

At the U.S. Open Tennis Championship a statistician keeps track of every serve that a particular player hits during the tournament.  The statistician reports that the mean speed of serves by this player was 100 mph and the standard deviation of his serves was 10 mph.  Three of the serves were clocked at 65, 110, and 120 mph.  Using the z-score approach for detecting outliers, which of these three serves represent outliers in the distribution of the speed of this player’s serves?

For a fixed confidence coefficient, the width of the confidence interval increases as the sample size increases.

Scientists want to estimate the difference in twinning rate of two lines of beef cattle that have been selected for increased frequency of twin births.  Last spring, 40 of the 100 cows in Line 1 gave birth to twins.  In Line 2, 30 of the 100 cows gave birth to twins. Construct a 90% confidence interval for the true difference in population proportions of cows giving birth to twins in Lines 1 and 2.  In the interest of time, you can assume that the sample sizes are large enough that it is appropriate to use a large-sample confidence interval.