In: Physics
The human body has a blood volume of about 5 liters (p = 1060 kg / m3). The total volume of blood with a cell density of 1225 kg / m3 turned out to contain 1% white blood cells and 44% red blood cells. Red blood cells 7.5 x 106 m in diameter. Determine the total number of blood cells in human blood
Ans. Human body has a blood volume (V) of about 5 L = 0.005 m3.
Density of blood cells,
= 1060 kg/m3.
Total mass of blood cells, 
kg
kg
Cell density,
= 1225 kg/m3.
Total cell volume, 

m3
Cell volume occupied by red blood cells (
)
= Total cell volume X 44%
= 
=
m3
Diameter of each red blood cell, d =
m
Volume of each red blood cell, v =
= 
=
m3
Number of red blood cells = 
= 
= 
Since, the white blood cells occupied 1% of total cell volume.
Then, the number of white blood cells will be
times the number of red blood cells.
Number of white blood cells =
= 
Therefore, total number of blood cells in human blood
= 
=
(Ans.)
N.B :: This problem basically belongs to biophysics. Any problem related to R.B.C, W.B.C, DNA, RNA etc. are very conceptual and interesting as well.
So, I highly recommend to follow up and practice these kind of problems regularly and boost your level up.