An investor is analyzing the risk of a possible investment based onthree differentscenarios.Under a pessimistic scenario, the property would produce a BTIRRpof 6%; a most-likely scenario produces a BTIRRpof 12%and anoptimistic scenario generates a BTIRRpof 19%.The investor assigns the pessimistic scenario a 25% chance of occurring, the most-likely case a 50% chance of occurring, and the optimistic scenario a 25% chance of occurring.What is the standard deviation of the returns?