use this link for questions 1 and 2, https://www.webassign.net/csalt/index.html#/toolset/distributions

Oxygen demand is a term biologists use to describe the oxygen needed by tish and other aguatic organisms for survivali The Enyirenmental protection Agency conducted a study of a wetland area. In this wetland enyirgnment, the mean oxygen demand was y : 91 mg/L with 95% ofthe data ranging from as rug/L10 11.9 mg/Li Let x be a mndom variable that represents oxygen demand in this wetland environment Assume x has a probability distribution that is approximately normal USE SA (a) Use the 95% data range ta estimate the standard deyiatisn for oxygen demand. E (b) All oxygen demand below 3 indicates that some organisms in the wetland enyironment may be dying what is the probability that the oxygen demand will fall belew 3 mg/L.' (Ruund your answer to tour decimal places) [c) A high oxygen demand can also inditate trsuble. An oxygen demand above 12 may inditate an overabundance of organisms that endanger same types nf plant life what is the pmbablllty that the oxygen demand will exceed 12 mg/L? [Round your answer to four decimal places) E Sketch the sampling distribution and show the area corresponding to the P-value. P - value O -4 -2 0 2 O -4 - 2 0 2 -4 -2 2 -2 0 2 (iv) Based on your answers to parts (i)-(iii), will you reject or fail to reject the null hypothesis? Are the data statistically significant at level a? O At the a = 0.01 level, we reject the null hypothesis and conclude the data are statistically significant. O At the a = 0.01 level, we fail to reject the null hypothesis and conclude the data are not statistically significant. At the a = 0.01 level, we fail to reject the null hypothesis and conclude the data are statistically significant. O At the a = 0.01 level, we reject the null hypothesis and conclude the data are not statistically significant. (v) Interpret your conclusion in the context of the application. O Fail to reject the null hypothesis, there is sufficient evidence to suggest that retail stocks have a higher percentage of stockholder equity when compared to utility stocks. O Fail to reject the null hypothesis, there is insufficient evidence to suggest that retail stocks have a higher percentage of stockholder equity when compared to utility stocks. O Reject the null hypothesis, there is insufficient evidence to suggest that retail stocks have a higher percentage of stockholder equity when compared to utility stocks. O Reject the null hypothesis, there is sufficient evidence to suggest that retail stocks have a higher percentage of stockholder equity when compared to utility stocks.| \\ How protable are different sectors of the stock market? One way to answer such a question is to examine profit as a percentage of stockholder equity. A random sample of 32 retail stocks such as Toys 'R' Us, Best Buy. and Gap was studied forxl, prot as a percentage of stockholder equity. The result was E1 : 14.7. A random sample of 37 y (gas and electric) stocks such as Boston Edison, wisconsin Energy, and Texas utilities was studied forxz, prot as a percentage of stockholder equity. The result was 21 : 11.1. Assume that U] 4.1 and 62 = 3.7. (a) Let 111 represent the population mean profit as a percentage of stockholder equity for retail stocks, and let p2 represent the population mean profit as a percentage of stockholder equity for utility stocks. Find a 95% condence interval forp1 p2. (Round your answers to two decimal places 3 (b) Examine the condence interval and explain what it means in the context of this problem. Does the interval consist of numbers that are all positive? all negative? of different signs? At the 95% level of confidence, does it appear that the profit as a percentage of stockholder equity for retail stocks is higher than that for utility stocks? 0 Because the interval contains only positive numbers, we can say that the profit as a percentage of stockholder equity is higher for retail stocks. 0 Because the interval contains both positive and negative numbers, we can not say that the profit as a percentage of stockholder equity is higher for retail stocks 0 We can not make any conclusions using this condence interval 0 Because the interval contains only negative numbers, we can say that the prot as a percentage of stockholder equity is higher for utility stocks. (c) Test the claim that the profit as a percentage of stockholder equity for retail stocks is higher than that for utility stocks. Use a = 0.01. (i) what is the level of signicance? E state the null and alternate hypotheses. O H04:1 : (12, H1: yr] : pz 0 HD' ltl : (12; H1: 111 p2 O H04:1 2.0 O Ho: M = 2.0; H 1: H > 2.0 O Ho: M = 2.0; H 1: H 0.500 O 0.250