It Is Desired to Determine the Blood Volume of a Live

Multiple Choice

It is desired to determine the blood volume of a live mouse.To do this,0.10 mL of a saline suspension of red blood cells labeled with Fe is injected into the tail vein.Before injection,the gamma rays were counted for this 0.10-mL solution and the count rate found to be 1.0 $\times$ 10⁴ cpm.After a sufficient time for the blood to be thoroughly mixed,0.10 mL of blood is removed and counted.The sample is found to have a count rate of 539 cpm.What is the approximate blood volume of the mouse?

A) 0.54 mL
B) 19 mL
C) 5.4 mL
D) 5.3 mL
E) 1.9 mL