Please provide specific equations and explanations. NO EXCEL!!! I need specific equations.

You are comparing stock A to stock B. Consider the following table:

State of Economy	Probability of State of Economy	Rate of Return if State Occurs
		Stock A	Stock B
Boom	60%	15%	9%
Normal	30%	8%	4%
Recession	10%	-2%	-5%

(a) What is the expected return of a portfolio which is comprised of $20,000 invested in stock A and $5,000 in stock B?

(b) What is the standard deviation of a portfolio which is comprised of $20,000 invested in stock A and $5,000 in stock B?

(c) Which one of these two stocks has a greater systematic risk? Assume that the expected return on the market portfolio is 7% and T-bills yield 2%..