The first midterm exam in Finance 4335 consists of 3 required problems.? Be sure to show your work as well as provide a complete answer for each problem; i.e., in addition to producing numerical results, also explain your results in plain English.
All three problems involve applications of expected utility.? I use only two types of utility functions in these problems; specifically, logarithmic (i.e., U(W) = ln W) and square root (i.e., U(W) = W.5).??A particularly important?concept on this exam involves knowing how to ?back into? the certainty equivalent of wealth (WCE) once you have calculated expected utility.? Hopefully this is a very familiar concept by now; once you have calculated E(U(W)), you set U(WCE) = E(U(W)) and solve for WCE.??Of course, once?you know WCE, then you also know the risk premium since the risk premium?is equal to?E(W) ??WCE.? Other important concepts to think about include the following:
- A utility function is risk averse/risk neutral/risk loving if marginal utility decreases/stays constant/increases as wealth increases; therefore, utility functions such as U(W) = ln W and?U(W) = W.5?are risk averse?because of diminishing marginal utility.??To see this,?note?that marginal utility in both cases is positive (which implies ?greed?); for U(W) = ln W, marginal utility is U?(W) = 1/W?> 0 and for U(W) = W.5, marginal utility is U?(W) = .5W-.5?> 0.? Furthermore, the rate of change in marginal utility in both cases is negative (which implies ?fear?); for U?(W) = 1/W,?U?(W) =?-1/W2 < 0, and for U?(W) = .5W-.5, U?(W) = -.25W-1.5?< 0.
- The Arrow-Pratt absolute risk aversion coefficients for U(W) = ln W and?U(W) = W.5 are 1/W and .5/W respectively.? Therefore, a person with utility U(W) = W.5 is less risk averse than a person with utility U(W) = ln W.? Furthermore, both utility functions imply decreasing absolute risk aversion, which means that as wealth increases, risk aversion associated with a specific gamble declines.
The formula sheet for the exam is available at http://fin4335.garven.com/fall2012/formulas_part1.pdf.? It will also be included as the last page of your exam booklet.
Source: http://risk.garven.com/2012/10/01/midterm-exam-1-information-2/
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