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Assume the mean length of time required to complete the Columbus Marathon was 4.5 hours and the standard deviation of the times was 0.70 hours.  Assume that the racing times were approximately normally distrubuted.  Only 10% of the runners would be expected to complete the race in less than x hours.  Find the value of x.

It is desired to estimate the average total compensation of CEO’s in the service industry.  Data were collected from 18 CEO’s and a 97% confidence interval was calculated to be ($2,181,260,  $5,836,180).  Which one of the following interpretations is correct?

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 none of the 4 patients will be alive at the end of 1 year?

A scientist conducts an experiment to determine if the mean alkalinity level of water specimens from the Olentangy River is greater than 50 milligrams per liter (mpl).  She selects a random sample of 100 water specimens from the river and finds a sample mean of 67.8 mpl and a sample standard deviation of 14.4 mpl.  She decides to test the hypothesis using a significance level of 0.01.  The critical value used to test this hypothesis is:

The average litter size in Ohio is approximately 8 pigs per litter.  Owners of a particular breed would like to prove that the mean litter size of their breed is greater than 8 pigs per litter.  Therefore, they want to test:      Ho:  μ = 8 pigs/litter      Ha:  μ > 8 pigs/litter They obtain a random sample of 100 litter size records from sows of this breed and find a sample mean of 8.4 pigs per litter and a sample standard deviation of 1 pig per litter.  They decide to use a significance level of α = 0.01. What is the appropriate test statistic needed to test the null hypothesis?

We want to test the hypothesis that the mean number of credit hours taken per semester by OSU undergraduates is less than 16 hours.  Therefore, we obtain a random sample of credit hours for 49 students. The sample mean is 15 hours and the sample standard deviation is 4 hours.  We want to test:    Ho:  μ = 16 hours    Ha:  μ < 16 hours using a significance level (α) = 0.01. What is the calculated value of the test statistic needed to test the null hypothesis in this problem?

We want to use a confidence interval to estimate the proportion of students in the College of Food, Agricultural, and Environmental Sciences that are female.  What sample size would be necessary if we want to estimate the true population proportion of female students correct to within 0.03 with probability 0.95?  In an earlier small-scale pilot study we obtained an estimate of the proportion of female students (p) that was equal to 0.48.

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.  Find the point estimate of the true difference in population proportions of cows giving birth to twins in Lines 1 and 2.

The objects (people, plants, animals, or things) upon which the response variable is measured are called the ____________.

Graphical methods of describing qualitative data include