Suppose that there are many stocks in the security market and that the characteristics of stocks A

Question:

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, rf. What must be the value of the risk-free rate? (Think about constructing a risk-free portfolio from stocks A andB.)

Stocks
Stocks or shares are generally equity instruments that provide the largest source of raising funds in any public or private listed company's. The instruments are issued on a stock exchange from where a large number of general public who are willing... Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...