i know this question is posted, but can the work be explained please, so step by step.

What is the standard deviation of the returns on a portfolio that is invested 52 percent in stock Q and 48 percent in stock R? Probability of State of Economy 10% 90% Returns if State Occurs Stock Q Stock R 14% 16% 8% 11% State of Economy Boom Normal 1.66 percent 2.47 percent 2.63 percent 3.28 percent 3.41 percent