DIG DEEPER!  Every 2 seconds, someone in the United States needs blood. A sample blood donation is shown. (1 mm3 $=10^{-3}$ mL) a. One cubic millimeter of blood contains about  $10^4$  white blood cells. How many white blood cells are in the donation? Responses 5 hundred thousand white blood cells 5 hundred thousand white blood cells 5 million white blood cells 5 million white blood cells 5 billion white blood cells 5 billion white blood cells 5 trillion white blood cells 5 trillion white blood cells Question 2 b. One cubic millimeter of blood contains about  $5\times10^6$  red blood cells. How many red blood cells are in the donation? Responses 2.5 thousand red blood cells 2.5 thousand red blood cells 2.5 million red blood cells 2.5 million red blood cells 2.5 billion red blood cells 2.5 billion red blood cells 2.5 trillion red blood cells 2.5 trillion red blood cells Question 3 c. Compare your answers for parts (a) and (b). The ratio of red blood cells to white blood cells is . Skip to navigation