Confidence Interval
Given a confidence level of .80 what is alpha?
What is .20
A large university reports that the mean salary of parents of an entering class is $91,600. To see how this compares to his university, a president surveys 28 randomly selected families and finds that their average income is $88,500. If the sample standard deviation is $10,000. What is the test statistic?
What is t=-1.64
For a certain year a study reports that the percentage of college students using credit cards was 83%. A college dean of student services feels that this is too high for her university, so she randomly selects 50 students and finds that 40 of them use credit cards. At a alpha= 0.04, with a test statistic of z=-.565 is there sufficient evidence to reject the null?
What is do not reject null. z=-.565
A study found that the average stopping distance of a school bus traveling 50 miles per hour was 264 feet. A group of automotive engineers decided to conduct a study of its school buses and found that for 20 buses, the average stopping distance of buses traveling 50 miles per hour was 262.3 feet. The standard deviation of the population was 3 feet. Test the claim that the average stopping distance of the company’s buses is actually less than 264 feet. Which function in Excel would you use to help calculate the p value?
What is Norm.Dist
What is a sampling distribution?
A distribution made up of numerous sample averages.
A hospital is trying to cut down on emergency room wait times. It is interested in the amount of time patients must wait before being call back to be examined. An investigation committee randomly surveyed 70 patients. The sample mean was 1.5 hours with a sample standard deviation of 0.5 hours. Assume that the underlying population distribution is normal. Which distribution should you use for this problem?
What is the T Distribution.
The following definition describes what? The decision is reject the null hypothesis when the null hypothesis is true.
What is Type I Error
In the Journal of the American Dietetic Association, it was reported that 54% of kids said that they had a snack after school. A random sample of 60 kids was selected, and 36 said that they had a snack after school. With a p value of .351 and a level of significance of 1%. Should you reject or fail to reject the null hypothesis?
What is fail to reject null. p=.351
According to the American Pet Products Manufacturers Association, cat owners spend an average of $179 annually in routine veterinary visits. A random sample of local cat owners revealed that 10 randomly selected owners spent an average of $205 with s = $26. Is there a significant statistical difference at a alpha= 0.01? Assume the amount cat owners spend is normally distributed. What function in Excel would you use to help calculate the pvalue?
What is t.dist.
The mean age for all Foothill College students for a recent Fall term was 33.2. The population standard deviation has been pretty consistent at 15. Suppose that twenty-five Winter students were randomly selected. The mean age for the sample was 30.4. We are interested in estimating the true mean age for Winter Foothill College students. Which distribution should you use to calculate the CI?
What is normal distribution.
The average undergraduate cost for tuition, fees, and room and board for two-year institutions last year was $13,252. The following year, a random sample of 20 two-year institutions had a mean of $15,560 and a standard deviation of $3500. Is there sufficient evidence at the a alpha= 0.01 to conclude that the mean cost has increased? What is the alternative hypothesis.
What is the population mean greater than $13,252?
What is the formula for a confidence interval for a large sample?
sample mean +/- Z ( sigma/sqrt of n)
For a hypothesis test. The p value is .012. If alpha is .05, what would the decision be for the hypothesis test?
What is reject the null hypothesis since p<alpha
The standard deviation of the weights of elephants is known to be approximately 15 pounds. We wish to construct a 95% confidence interval for the mean weight of newborn elephant calves. Fifty newborn elephants are weighed. The sample mean is 244 pounds. The sample standard deviation is 11 pounds construct a 95% CI for the population mean weight.
What is CI: (239.84, 248.16)
A state executive claims that the average number of acres in western Pennsylvania state parks is less than 2000 acres. A random sample of five parks is selected, and the number of acres is shown. At a alpha? 0.01, is there enough evidence to support the claim? Calculate the test statistic.
What is t=-.103
What is the formula for a confidence interval for a small sample, with the original distribution normally distributed and the population standard deviation is unknown?
What is sample mean +/- t (sample std dev/sqrt(n))
A researcher claims that the yearly consumption of soft drinks per person is 52 gallons. In a sample of 50 randomly selected people, the mean of the yearly consumption was 56.3 gallons. The standard deviation of the population is 3.5 gallons. Find the P-value for the test. On the basis of the P-value, is the researcher’s claim valid?
What is p=3.76e-18. Reject null
If the alternative hypothesis is the population mean is less then 20. Is this a right tail, left tail or two tail test?
What is a left tail test.
The U.S. Census Bureau conducts a study to determine the time needed to complete the short form. The Bureau surveys 200 people. The mean mean is 8.2 minutes. There is a known standard deviation of 2.2 minutes. The population distribution is assumed to be normal. Construct a 90% confidence interval for the population mean time to complete forms.
What is CI: (7.9441, 8.4559)
Full-time Ph.D. students receive an average salary of $12,837 according to the U.S. Department of Education. The dean of graduate studies at a large state university feels that Ph.D. students in his state earn more than this. He surveys 44 randomly selected students and finds their average salary is $14,445, and the population standard deviation is $1500. With a alpha 0.05, is the dean correct?
What is reject the null. z=7.11
What is following theorem called:
If size n of the sample is sufficiently large, then the distribution of the sample means will approximate a normal distribution regardless of the shape of the population. The mean of the sample means will equal the population mean. The standard deviation of the distribution of the sample means is sigma divided by the square root of n.
What is the Central Limit Theorem.
True or false: The null hypothesis always has a statement of equality.
What is true.