Question

calculate the medullary index of a hair with a diameter of 5.3 and a medulla of 2.2. is this hair human or animal?
select one:
○ a. the index is 0.24, and the hair is human.
○ b. the index is 0.42, and the hair is human.
○ c. the index is 0.42, and the hair is animal.
○ d. the index is 0.24, and the hair is animal.
check

Explanation:

Step1: Calculate the medullary index

The formula for the medullary index is $\frac{\text{medulla diameter}}{\text{hair diameter}}$.
Substitute the given values: $\frac{2.2}{5.3}\approx0.42$.

Step2: Determine if the hair is human or animal

For human hair, the medullary index is generally less than $0.33$. For animal hair, it is usually greater than $0.5$. But in some cases (e.g., some animal hairs can have medullary index around $0.4 - 0.5$). Given the options and the calculated index of $0.42$, we go by the general rule of thumb for the given multiple - choice context.

Answer:

C. The index is 0.42, and the hair is animal.