Evan has a portfolio with two stocks. He invested 50% into stock A with a standard deviation of 12%, and the remaining into stock B with a standard deviation of 13%. The correlation between the two stocks is 0.67. What is the standard deviation of Evan’s portfolio? (Round your answer as decimals with four decimal places, such as 0.1234. For example, if your answer is 12.34%, write 0.1234. DO NOT write your answer as percentages as you will be marked wrong.)