Consider the following model:

$w_{\text{r}\text{i}\text{s}\text{k}\text{y}}=\frac{E[R_M]-r_f}{{}^{2}A}$

What is the degree of risk aversion required such that an investor

would put $100\%$ of his portfolio in the risk$-$free asset? $($i$.$e$.$

$($:$w_{\text{r}\text{i}\text{s}\text{k}\text{y}}=0\}$

$A=$ infinity

$A=0$

$A=3\mathrm{.}5$

$A=$ Average of all investors

$A=$exp$(R^{**}T)$