Draw a scale of 1:50 to read meters and decimeters.

We assume a convenient maximum length to be measured, for example, 5 meters.
The formula for the Length of the Scale (LOS) is:

$$\text{LOS} = \text{R.F.} \times \text{Maximum length}$$

Given R.F. = $1:50$ and Maximum length = $5 \text{ meters}$.
Convert meters to centimeters for drawing: $1 \text{ meter} = 100 \text{ cm}$.

$$\text{LOS} = \frac{1}{50} \times (5 \times 100) \text{ cm}$$ $$\text{LOS} = \frac{1}{50} \times 500 \text{ cm}$$ $$\text{LOS} = 10 \text{ cm}$$

So, the total length of the scale to be drawn on paper will be $10 \text{ cm}$.

The $10 \text{ cm}$ line represents $5 \text{ meters}$.

• Primary Divisions (for meters): Divide the $10 \text{ cm}$ line into 5 equal parts. Each part will represent $1 \text{ meter}$. Length of each primary division = $\frac{10 \text{ cm}}{5} = 2 \text{ cm}$.
• Secondary Divisions (for decimeters): The leftmost primary division represents $1 \text{ meter}$. Since $1 \text{ meter} = 10 \text{ decimeters}$, this $2 \text{ cm}$ segment needs to be divided into 10 equal parts. Length of each secondary division = $\frac{2 \text{ cm}}{10} = 0.2 \text{ cm}$. Each of these will represent $1 \text{ decimeter}$.

1. Draw a horizontal line segment $10 \text{ cm}$ long.
2. Divide this line into 5 equal main parts, each $2 \text{ cm}$ long.
3. Mark the main divisions starting from the second mark from the left as $0, 1, 2, 3, 4 \text{ meters}$. The first main division (to the left of 0) is reserved for decimeters.
4. Divide the leftmost main division (the $2 \text{ cm}$ segment to the left of 0) into 10 equal sub-parts, each $0.2 \text{ cm}$ long.
5. Mark these sub-divisions as $0, 2, 4, 6, 8, 10 \text{ decimeters}$ (or $0, 1, 2, ..., 10$ if space allows).
6. Draw a rectangle around the scale and add text labels: "R.F. = 1:50", "Meters" below the main divisions, and "Decimeters" below the sub-divisions.

The final scale will be a $10 \text{ cm}$ line representing $5 \text{ meters}$, with main divisions of $2 \text{ cm}$ for meters and sub-divisions of $0.2 \text{ cm}$ for decimeters.