Question

A 100-meter skein of polyester filament yarn weighs 2.5 grams, calculate its tex number.

• A. 12 tex
• B. 25 tex
• C. 17 tex
• D. 21 tex

Hint:

The definition of Tex is simply "grams per 1000 meters". If you are given the weight for any other length, just calculate how much 1000 meters would weigh. In this case, 100m is 2.5g, so 1000m (10 times longer) must be 10 times heavier: \(2.5 \times 10 = 25\text{g} \rightarrow 25 \text{ tex}\).

Answer 1

The Correct Option is B

Step 1: Define the Tex system. The Tex system is a direct yarn numbering system. The Tex number is defined as the weight in grams of 1,000 meters of yarn.
Formula: Tex = Weight (g) / Length (km) = Weight (g) for 1000m.

Step 2: Use the given data to find the weight per 1000 meters.
Given: - Length = 100 meters - Weight = 2.5 grams We can set up a proportion: If 100 meters weigh 2.5 grams, Then 1000 meters will weigh X grams.
\[ \frac{2.5 \, \text{g}}{100 \, \text{m}} = \frac{X \, \text{g}}{1000 \, \text{m}} \]

Step 3: Solve for X.
\[ X = \frac{2.5 \times 1000}{100} = 2.5 \times 10 = 25 \] So, 1000 meters of the yarn weigh 25 grams.

Step 4: Determine the Tex number.
By definition, the Tex number is the weight in grams per 1000 meters. Therefore, the yarn count is 25 tex.