a) Tania is a young passionate investor who needs to achieve financial independence through investing money she received from her parents. To initiate this new adventure, she has selected 2 stocks portfolios. She has decided to invest 30% of her money in Stock X with rate of return of 20%. The rest of her money will be invested in stock Y which is less risky than stock X with an annual rate of return of 15%. Based on the above information, calculate the portfolio return.

b) The upcoming financial year forecast of the economic status and returns of the portfolio will be as follows: State of economy Probability Rate of returns on portfolio investment Mild Recession 0.20 - 5% Growth 0.50 15% Strong Growth 0.30 30% Calculate the expected return, variance and standard deviation of the portfolio.

c) Discuss the use of variance and standard deviation of return on investment decision-making?