1. **Problem statement:**
(a) Given the scale of a map is 1 : 250000, and the actual distance between two cities is 80 km, calculate the distance on the map in centimetres.
2. **Formula and explanation:**
The scale means 1 cm on the map represents 250000 cm in reality.
3. **Convert actual distance to centimetres:**
Since 1 km = 100000 cm,
$$80\text{ km} = 80 \times 100000 = 8000000 \text{ cm}$$
4. **Calculate map distance:**
Using the scale,
$$\text{Map distance} = \frac{\text{Actual distance}}{\text{Scale factor}} = \frac{8000000}{250000}$$
5. **Simplify the fraction:**
$$\frac{\cancel{8000000}}{\cancel{250000}} = 32$$
6. **Answer for (a):**
The distance on the map is **32 cm**.
1. **Problem statement:**
(b) On the map, a forest area is 6 cm². Calculate the actual area in square kilometres.
2. **Formula and explanation:**
Area scale factor is the square of the linear scale factor.
3. **Calculate actual area:**
$$\text{Actual area} = \text{Map area} \times (\text{Scale factor})^2 = 6 \times (250000)^2$$
4. **Calculate:**
$$(250000)^2 = 62500000000$$
5. **Multiply:**
$$6 \times 62500000000 = 375000000000 \text{ cm}^2$$
6. **Convert cm² to km²:**
Since $1 \text{ km}^2 = (100000 \text{ cm})^2 = 10000000000 \text{ cm}^2$,
$$\text{Actual area} = \frac{375000000000}{10000000000} = 37.5 \text{ km}^2$$
7. **Answer for (b):**
The actual area of the forest is **37.5 km²**.
Map Scale Dcef77
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