Exam 9: Testing the Difference Between Two Means, Two Variances, and Two Proportions

A conservationist wants to know if the water level (in meters) in Crab Lake is more or less variable than the water level in Gull Lake.If one tested the hypothesis that the levels are equally variable at the critical value would be

The critical value for a two-tailed F -test is 2.65, when the sample size from which the variance for the numerator was obtained = 10, and the sample size from which the variance for the denominator was obtained = 15.

Compute the critical value for a right-tailed F -test with d.f.N.= 21, and d.f.D.= 20.

When hypothesizing a difference of 0, if the confidence interval does not contain 0, the null hypothesis is rejected.

A car salesman claims that the variance of prices on convertibles is higher than the variance on station wagons.The standard deviation of 16 convertibles is $6,800 and the standard deviation of 24 station Wagons is $3,900.For α = 0.05, what is the test value?

An educational researcher is analyzing the test scores for statistics students taught using two different methods - a traditional method and a web-based, self-paced method.Can he Conclude, at , that the test scores in the web-based, self-paced method are lower?

When testing the difference between two proportions, one sample had 30 out of 100 who were for capital punishment, and the other sample had 60 out of 80 who were for capital punishment.Calculate the Standard error.

What is the critical value for a two-tailed F -test with when the sample size from which the variance for the numerator was obtained was 10, and the sample size from which the denominator was Obtained was 24?

The standard error of difference of two large (independent) sample means is .

A college class believes that the average grade averages of psychology students and the average grade averages of biology students are different.The class found that the actual grade averages of a sample of 10 psychology students was 3.2, and the average grade average of a sample of 10 biology students was2.9.What is the null hypothesis for this study?

One poll found that 40% of male voters will support a candidate while another found that 48% of female voters will be in support.To test whether this candidate has equal levels of support between male and Female voters, the alternative hypothesis should be

A study on the oxygen consumption rate (OCR) of sea cucumbers involved a random sample of size 10 at 15oC and second random sample of size 7 kept at 18oC.If one tested the hypothesis that this range of Temperature had no effect on the OCR (assume equal variability) the critical value would be (assume =.05)

A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol.As part of this trial, they wish to determine whether there is a difference in effectiveness between women and men. At = .05, what is the test value?

In testing the equality of the two means below, what is the test statistic? (Use the equal variances formula)

When the subjects are paired or matched in some way, samples are considered to be __________. ________________________________________

A researcher wanted to determine if using an octane booster would increase gasoline mileage.A random sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks with the booster. -State the alternative hypothesis.

A researcher hypothesizes that the variation in the car rental rates at a major citiy's airport is less than the car rental rates in that city.The variance of 7 airport car rental rates was $25 and the variance of 4 city car Rental rates was $60.What is the test value?

A pooled estimate of the variance is a weighted average of the variance using the two sample variances and the __________ of each variance as the weights. ________________________________________

A medical researcher is interested in whether patients' left arms or right arms are longer.If 9 patients participate in this study (so that 9 left arms and 9 right arms are measured), how many degrees of freedom Should the researcher use in her t-test critical value?

A researcher hypothesizes that the variation in the amount of money spent on business dinners is greater than the amount of money spent on lunches.The variance of nine business dinners was $6.12, and the Variance of 12 business lunches was $0.87.What is the test value?