Question

question 3
the diameter of a white blood cell is about ( 1.5\times10^{-5} ) meter. the diameter of a red blood cell is about ( 7.5\times10^{-6} ) meter. which statement is true?
the diameter of a red blood cell is about 50 times the diameter of a white blood cell.
the diameter of a red blood cell is about 5 times the diameter of a white blood cell.
the diameter of a white blood cell is about 2 times the diameter of a red blood cell.
the diameter of a white blood cell is about 20 times the diameter of a red blood cell.

Explanation:

Step1: Calculate the ratio of the diameter of white blood cell to red blood cell

We use the formula for ratio \(r=\frac{\text{diameter of white blood cell}}{\text{diameter of red blood cell}}\). Given diameter of white blood cell \(d_w = 1.5\times10^{-5}\) and diameter of red blood cell \(d_r=7.5\times 10^{-6}\). Then \(r=\frac{1.5\times 10^{-5}}{7.5\times 10^{-6}}\).
Using the rule of exponents \(\frac{a\times10^{m}}{b\times 10^{n}}=\frac{a}{b}\times10^{m - n}\), we have \(\frac{1.5}{7.5}\times10^{-5-(-6)}\).
\(\frac{1.5}{7.5}=0.2\) and \(10^{-5 + 6}=10^{1}\). So \(r = 0.2\times10^{1}=2\).

Answer:

The diameter of a white blood cell is about 2 times the diameter of a red blood cell.