A bank is considering adding security underwriting services to the services it offers. It has estimated that the expected return and standard deviation of its traditional service are 8% and 10% respectively. It has estimated that the expected return and standard deviation of its new securities underwriting services are 16% and 20% respectively. The correlation between these services has been estimated to be -.3 and the bank estimates that 85% of its business will be from traditional services and 15% from the new services. What is the standard deviation of the new combined firm?