Scientists are interested in determining if the mean alkalinity level of water specimens from the Han River in Seoul, Korea is greater than 50 milligrams per liter (mpl).  They select a random sample of 100 water specimens from the river and find a sample mean of 70 mpl and a sample standard deviation of 15 mpl.  They decide to test the hypothesis that the population mean for alkalinity level of water in the Han River exceeds 50 mpl using a significance level of 0.01.  Should the scientists reject or not reject the null hypothesis?  Explain.

A Gallop poll is conducted to estimate the proportion of voters who plan to vote in favor of a certain issue on the ballet.  A random sample of 500 people of voting age is selected.  Results of the poll show that 300 of the 500 people polled plan to vote in favor of the issue.  Construct a 99% confidence interval for the true population proportion of people who plan to vote in favor of the issue.

An animal scientist conducts a study to estimate the proportion of cows of the Charolais breed that require assistance during calving.  A random sample of 500 Charolais cows is selected.  Results of the study show that 100 of the 500 cows in the sample required assistance in giving birth.  What is the point estimate of the true population proportion (p) of Charolais cows that require assistance during calving?

The ____________ ____________ is the probability that a confidence interval encloses the true value of the population parameter, if the confidence interval procedure is used repeatedly a large number of times.

The range of a population is approximately equal to __________.  (Hint:  remember the Empirical Rule)

A large labor union wishes to estimate the mean number of hours per month that union members are absent from work.  The union samples 475 of its members at random and monitors their working time for 1 month.  At the end of the month, the total number of hours absent from work is recorded for each employee.  The mean and standard deviation of the sample are 9.6 hours and 3.6 hours, respectively.  What is the point estimate of the mean (μ) of the entire population of number of hours absent from work per month?

Suppose x has a binomial probability distribution with n = 400 and p = 0.70.  Use the normal approximation to the binomial to find P (X 

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 variance of the grades of these 8 students.

Toyota would like to know how many miles per gallon the average driver gets when driving the hybrid Toyota Prius.  A random sample of 225 drivers yields a mean of 50 mpg and a standard deviation of 7.5 mpg. Estimate the population mean for the miles per gallon of the Prius using a 90% confidence interval.

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 critical value that should be used to test the null hypothesis?