Stock S is expected to return 12 percent in a boom, 9 percent in a normal economy, and 2 percent in a recession. Stock T is expected to return 4 percent in a boom, 6 percent in a normal economy, and 9 percent in a recession. There is a 10% probability of a boom, and a 25 percent probability of a recession. What is the standard deviation of a portfolio which is comprised of $4500 in Stock S and $3000 of Stock T?