4. [13 Points] WACKERLYSTA'I'I 7.2.021. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER The Environmental Protection Agency is concerned with the problem of setting criteria for the amounts of certain toxic chemicals to be allowed in freshwater lakes and rivers. A common measure of toxicity for any pollutant is the concentration of the pollutant that will kill half of the test species in a given amount of time (usually 96 hours for sh species). This measure is called LCSO (lethal concentration killing 50% of the test species). In many studies, the values contained in the natural logarithm of LCSO measurements are normally distributed, and, hence, the analysis is based on ln(LC50) data. Suppose that n = 25 observations are to be taken on |n(LC5[J) measurements and that 0'2 = 1.9. Let 52 denote the sample variance of the 25 measurements. (a) Find a number [I such that .F'(S2 S b) : 0.975. (Round your answer to three decimal places.) (b) Find a number a such that P(a s 52) : 0.975. (Round your answer to three decimal places.) (c) [fa and b are as in parts (a) and (b), what is P(a S 52 s b)? (Round your answer to two decimal places.) Wk: You may need to use the appropriate appendix table or technology to answer this question. Need Help