Suppose that there are many stocks in the security market and that the

characteristics of stocks A and $B$ are given as follows:

Suppose that it is possible to borrow at the risk$-$free rate, $r_f.$ What must be the

value of the risk$-$free rate? $($Hint: Think about constructing a risk$-$free portfolio

from stocks A and $B.)($Do not round intermediate calculations. Round your

answer to $3$ decimal places.$)$