Suppose that R1 and R2 are two stock returns, and assume further that these returns are independent and identically distributed, P(R1=1.2)=P(R2=1.2)=21,P(R1=1.0)=P(R2=1.0)=21. Suppose that there is another security with a risk-free return Rf=1.05. (a) How many scenarios are needed to describe the joint distribution of R1 and R2