Question

The radius of the Earth is $$6400\ km$$ and that of Mars is $$4300000\ m$$. Whose radius is bigger and by how much?

Answer 1

$$\textbf{Step 1: Conversion of unit from m to km}$$

We know that $$1000\ m = 1\ km$$

$$\therefore$$ $$1\ m = \dfrac{1}{1000}\ km$$

$$\therefore$$ $$4300000\ m = \dfrac{1}{1000} \times 4300000\ km$$

Therefore radius of mars $$= 4300\ km$$

$$\textbf{Step 2: Finding the difference of radii}$$

Difference of radius of Earth and Mars $$=$$ Radius of Earth - radius of Mars

$$= 6400\ km - 4300\ km$$

$$= 2100\ km$$

$$\textbf{Hence, the radius of Earth is bigger than the radius of Mars by 2100 km}$$