Independent random samples of sizes n1 = 30 and n2 = 50 are taken from two normal populations hav-ing the means μ1 = 78 and μ2 = 75 and the variances σ21 = 150 and σ2 2 = 200. Use the results of Exercise 3 tofind the probability that the mean of the first sample willexceed that of the second sample by at least 4.8.

A nutrition store in the mall is selling "memory booster" which is a concoction of herbs and minerals that is intended to improve memory performance. To test the effectiveness of the herbal mix, a researcher obtains a sample of n=16 participants and has each person take the suggested dosage each day for 4 weeks. At the end of the four week period, each individual takes a standard memory test. The scores from the participants produced a M=26 with a sample variance of s2=64. In the general population, the standardized test is known to have a μμ=20. Do the sample data support the conclusion that memory booster has a significant effect? Use a two-tailed test with αα=.05. Compute Cohen's d to measure the size of the treatment effect.

A study was conducted to compare the length of time between men and women to assemble a certain product. Sample standard deviation in a random sample of times for 11 men was 8.6 minutes, and sample standard deviation in a random sample of times for 13 women was 6.9 minutes. Past experience indicate that population of times is normal for both men and women. Is it sufficient sample evidence to conclude that the variance of the lengths of time for men is larger than the variance of the lengths of time for women? Test appropriate hypothesis at a = 0.05 level of significance using critical value approach. Use S²/S2 as test statistic. Construct a 90% confidence interval for the ratio of two population variances. a. State null and research hypotheses H: H₁ b. The observed value of test statistic is c. State the rejection region d. Insert the word sufficient or insufficient into the following statement. There is of time for men is larger than the variance of the lengths of time for women.…

We are running a hypothesis test to see if weight of African zebras is significantly different than that of Arabian horses. We assume weight in both populations is normally distributed and both populations have the same population variance in weight which is unknown to us, so we use the sample variances to estimate the standard error for our calculations. We have a sample of size 9 for the African zebras with mean 650 and a sample of size 16 for the Arabian horses with mean 659. If the pooled variance is 81, then what is the absolute value of the standardized test statistic for our data?

A sample with SS=30 and a variance of s2 =10 has n=4 scores. True or False?

A professor claims that the final exam grades are more widely dispersed in Principles classes compared to upper-level classes. In a sample of 101 Principles final exams, the standard deviation is 16 while in a sample of 30 upper-level class final exams the standard deviation is 13. Test the hypothesis at the 10% level of significance that the 2 variances are different. Write all formulas and hypothesis.

A dietician is researching two new weight gain supplements that have just hit the market: Ripped and Gainz. She wants to determine if there is any difference between the two supplements in the mean amount of weight gained (in kg) by the people who take them. The dietician tracks the total weight gain (in kg) over a year of a random sample of 14 people taking Ripped and a random sample of 12 people taking Gainz. (These samples are chosen independently.) These data are shown in the table. Total weight gains (in kg) Ripped Gainz 14.1, 10.9, 12.1, 5.2, 12.0, 17.1, 9.0, 14.8, 11.2, 6.8, 12.4, 8.5, 12.1, 10.5 Send data to calc... v 7.6, 9.5, 8.6, 10.8, 7.9, 10.0, 8.4, 6.2, 8.6, 10.2, 8.9, 8.2 Send data to Excel Assume that the two populations of weight gains are approximately normally distributed. Can the dietician conclude, at the 0.05 level of significance, that there is a difference between the population mean of the weights gained by people taking Ripped and the population mean of the…