Portfolio return is a weighted average of stated asset returns.
Stated inputs
Asset A has stated return 10% and asset B has stated return 6%. A fifty-fifty portfolio uses weight 1/2 in each asset.
wA=wB=1/2,rA=10%,rB=6%
Weighted average return
Portfolio return is the weighted average of the stated returns. Here it is 8%, independent of correlation.
rp=wrA+(1−w)rB=8%
Inputs, not estimates
In the real world, returns, sigma, and rho are estimated from data with uncertainty. Here they are stated exact model inputs. This is descriptive, not investment advice.
stated inputs, exact arithmetic