Answer:
D. 3*10^2
Explanation:
Given the diameter of human red blood cell = 0.000009 m
diameter of a cold virus = 0.00000003 m
To know how many times as large is the diameter of a red blood cell as the diameter of a cold virus, we will take the ratio of the diameter of human red blood cell to that of a cold virus as shown;
diameter of human red blood cell/diameter of a cold virus = 0.000009 m/0.00000003 m
= 9*10^-6/3*10^-8
= 9/3 * 10^-6-(-8)
= 3 * 10^(-6+8)
= 3*10^2
Hence the diameter of a red blood cell is 3*10^2 larger than that of the cold virus