A random of 15 freshmen takers obtained a mean score of 74 and a variance of 9 on a SASE. Assuming the scores to be normally distributed, construct a 95% confidence interval to estimate the variance of scores of the whole freshmen population.

A behavioral researcher measures the stress response of mice exposed to scary animal pictures (cat, dog, lion, Cheshire cat) with a GABA sensor implanted in the brain. He uses randomly assigned 40 mice, 10 in each group. The researcher records the amount of stress after 30 seconds assuming that there is no difference in the response in whatever way the mouse is scared. The data is normally distributed. Means and variances are provided in the table below. Is there a difference in the response to scary animals. Group 1 - Cat n₁=10 m₁ = 10 s² 1= 1.8 Group 2 - Dog n2=10 m₂= 5.0 s²2= 3.4 Why is the scare effect so low in group 4? Group 3 - Lion n3=10 m3= 3.4 s²1= 2.5 Group 4 - Chesire Cat n4=10 m4= 2.4 s² 1= 1.6

An educator has developed a program to improve math scores on the Texas STAAR test. The average STAAR Mathematics test for the third graders in the district was a mean= 1472. A sample of n= 30 third graders took the new math training prgram before taking the STAAR Math test. The average score for the students was M= 1497. with a standard deviation of s= 145 (note, this is standard deviation, not variance).  Was there a significant change in test scores ( use stard devistion of 0.05, two tail test).    Calculate the effect size using Cohen's d.

A researcher decides to measure anxiety in group of bullies and a group of bystanders using a 23-item, 3 point anxiety scale.  Assume scores on the anxiety scales are normally distributed and the variance among the group of bullies and bystanders are the same. A group of 30 bullies scores an average of 21.5 with a sample standard deviation of 10 on the anxiety scale.  A group of 27 bystanders scored an average of 25.8 with a sample standard deviation of 8 on the anxiety scale. You do not have any presupposed assumptions whether bullies or bystanders will be more anxious so you formulate the null and alternative hypothesis based on that.

The blood pressure and weight of Jellystone Park bears are correlated and .5 is the correlation coefficient of blood pressure with weight.  The average blood pressure is 150 with variance 36, for Jellystone Park bears.  For a randomly selected bear with average weight if we predict its blood pressure is 150 after weighing it, using SLR, what is our expected squared error?