Portfolio B consists of 15 stocks, 10 of which have beta 1 and idiosyncratic variance 0.02, and 5 of which have beta 1 and idiosyncratic variance 0.04. What is the minimum idiosyncratic variance one can achieve by investing in these stocks? You should assume that the idiosyncratic risks of the stocks included in B are independent across stocks. (Hint: the portfolio that minimises the idiosyncratic variance has equal weights in stocks with the same idiosyncratic variance)