help me figure put steps 1 - 7 of questions a - b

Normal probability distribution Assuming that the rates of return associated with a given asset investment are normally distributed; that the expected retum, rf is 19.2%; and that the coefricient of variation, CV, is 0.24 , answer the following questions: a. Find the standard deviation of returns, r b. Calculate the range of expected return outcomes associated with the following probabilities of occurrence: (1) 68%, (2) 95%, (3) 99% a. The standard deviation of returns, f is %. (Round to three decimal places.)