Final answer:
To calculate the volume of RBC needed to make a 4% red cell suspension, you need the initial concentration, which is not provided in the question.
Step-by-step explanation:
To calculate the volume of RBC needed to make a 4% red cell suspension, we can use the formula C₁V₁ = C₂V₂, where C₁ is the initial concentration, V₁ is the initial volume, C₂ is the desired concentration, and V₂ is the desired volume.
In this case, we are given that the desired volume (V₂) is 25 mL and the desired concentration (C₂) is 4%. We need to find the initial volume (V₁). Since the initial concentration (C₁) is not given, we cannot directly calculate V₁. Without additional information regarding the initial concentration, we cannot provide a specific answer to this question.