By the virial theorem, the total mass of the cluster should be 5 R ⟨ ⟨ v r 2 ⟩ ⟩ G ≈ ≈ 3.6 × × 10 14 M ⊙ ⊙ . However, the observed mass is N m = 8 × × 10 11 M ⊙ ⊙ , meaning the total mass is 450 times that of observed mass.