To determine the distance Earth should be placed from the dot in the scale model, we can set up a proportion based on the distances of Mercury and Earth from the Sun.
We know:
- Mercury's real distance from the Sun: 60,000,000 km
- Mercury's model distance from the Sun: 10 cm
- Earth's real distance from the Sun: 150,000,000 km
We can set up a ratio to find Earth's model distance:
\[ \frac{\text{Distance of Earth}}{\text{Distance of Mercury}} = \frac{\text{Model distance of Earth}}{\text{Model distance of Mercury}} \]
Substituting the known values:
\[ \frac{150,000,000 \text{ km}}{60,000,000 \text{ km}} = \frac{x \text{ cm}}{10 \text{ cm}} \]
Calculating the left side:
\[ \frac{150,000,000}{60,000,000} = 2.5 \]
Now substituting back into the proportion:
\[ 2.5 = \frac{x}{10} \]
To find \(x\):
\[ x = 2.5 \times 10 = 25 \text{ cm} \]
So Earth should be placed at a distance of 25 cm from the dot in the model.
The correct answer is 25 cm.