效益费用比(RBC)是指项目在计算期内效益流量的现值与费用流量的现值之比. 费用流量的现值 = 100 + 0.8/(1+0.1) + 0.8/(1+0.1)^2 + ... + 0.8/(1+0.1)^10 = 104.9156537效益流量的现值 = 20/(1+0.1) + 20/(1+0.1)^2 + ... + 20/(1+0.1)^10 = 122.8913421效益费用比(RBC) = 效益流量的现值/费用流量的现值 = 1.171334665