STAT 3000 Midterm Exam 3 Practice Problems - Prof. Mevin B. Hooten, Exams of Statistics

Download STAT 3000 Midterm Exam 3 Practice Problems - Prof. Mevin B. Hooten and more Exams Statistics in PDF only on Docsity! STAT 3000: Midterm Exam 3 Practice Problems Dr. Mevin Hooten Instructions: 1.) Show all work (zero credit will be awarded if answers are not substantiated) 2.) Calculators and one sheet of formulae are allowed 3.) Final answers need to be accurate to at least 3 decimal places for full credit 1.) Animal scientists are interested in various comparisons of cattle susceptibility to foot and mouth disease in the USA versus Europe. The two populations of cattle were randomly and independently sampled. The measurements taken on the cattle were based on a continuous susceptibility scale where the higher scores correspond to more susceptible animals. The distribution of this population of scores is known to be normal. Sample Statistics: USA € x 1=10 s12=9 n1=21 Eur. € x 2=14 s22=4 n2=21 a.) Is there reason for the scientists to believe that the two populations have the same variability? (Support your decision and use an alpha level of 0.1.) b.) Regardless of what you found in part a, assume the population variances are unequal. Is there supporting evidence to conclude that European cattle are more susceptible on average than American cattle (alpha=0.05). c.) Calculate an 80% confidence interval for the difference in mean scores between USA and European cattle. 2.) State government agents would like to estimate the average amount of feed consumed by pigs in a given week in Utah. They would like to be 90% confident in their estimate. They randomly sampled 36 pigs across the state and inquired about how much they ate in a week. The sample mean was 100 pounds with a sample variance of 25 pounds. Help them find the appropriate interval estimate. 3.) In order to determine if sheep gain a significant amount of weight when subjected to a growth hormone, 4 mature sheep were randomly selected and they were weighed before and after the treatment was administered. Use an alpha level of 0.05 to determine if the hormone was effective in increasing weight and assume differences are normally distributed. The weights are listed in pounds below. Pre-Treatment Post-Treatment Diffs Sample Stats for Diffs: 50 60 -10 40 45 -5 Mean = -3.75 60 55 5 Std. Dev. = 6.29153 50 55 -5