Either Galatasaray (GS) or Fenerbahce (FB) will be the champions this season. If GS are the champions, GS stock will go up by 20% and FB stock will go down by 30%. If FB are the champions, FB stock will go up by 40% and GS stock will go down by 10%. The chances that GS are the champions this season is 60%. What is the standard deviation of the portfolio returns that invests 50% in the GS stock and 50% in the FB stock? Round to the nearest first decimal.