Statistics: Variance and Vanguard Total Stock Essay

653 WordsDec 29, 20113 Pages
Statistics Midterm paper 1. : Identify the implied population in the information here. Government agencies carefully monitor water quality and its effect on wetlands (Reference: Environment Protection Agency Wetland Report EPA 832-R-93-005). Of particular concern is the concentration of nitrogen in water draining from fertilized lands. Too much nitrogen can kill fish and wildlife. Twenty-eight samples of water were taken at random from a lake. The nitrogen concentration (milligrams of nitrogen per liter of water) was determined for each sample. The variable in this information is nitrogen concentration (mg nitrogen/l water). a. number of fish b. samples of water taken at random c. the wetlands d. nitrogen concentration (mg…show more content…
147 153 167 174 182 178 179 182 178 178 167 0 153 144 a. 144 b. 182 c. 167 d. 153 e. 178 5. Find the sample variance s2 for the following sample data. Round your answer to the nearest hundredth. x: 23 17 12 35 29 a. 84.20 b. 67.36 c. 101.00 d. 88.84 e. 126.25 6. Do bonds reduce the overall risk of an investment portfolio? Let x be a random variable representing annual percent return for the Vanguard Total Stock Index (all Stocks). Let y be a random variable representing annual return for the Vanguard Balanced Index (60% stock and 40% bond). For the past several years, assume the following data. Compute . x: 14 0 36 23 33 25 26 14 14 23 y: 6 5 26 17 24 17 17 5 6 6 a. 4607 b. 4803 c. 5332 d. 4243 e. 4940 Answers: Queston 1: The population is d. - the nitrogen population in the entire lake. Question 2: The technique is a census since all events are to be measured. Question 3. The Pareto Chart is below:[pic] Question 4: The mode is the most frequently occurring value in a set of data so here the mode is 178 so the answer is e. Question 5. The samplle variance is 84.20 so the answer is a. Question 6. The mean return for the Vanguard Total Stock Index is 20.8 while the mean return for the Vanguard Balanced Index is 12.9 (with bonds). Based on this data you would conclude that bonds do not reduce the overall risk of an investment portfolio since the mean return was actually less when the porfolio has bonds in
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