Blue Bell stock is expected to return 8.4 percent in a boom, 8.9 percent in a normal economy, and 9.2 percent in a recession. The probabilities of a boom, normal economy, and a recession are 6...

Blue Bell stock is expected to return 8.4 percent in a boom, 8.9 percent in a normal economy, and 9.2 percent in a recession. The probabilities of a boom, normal economy, and a recession are 6 percent, 92 percent, and 2 percent respectively. What is the standard deviation of the returns on this stock?

Can the calculator an excel solution be provided?