1. **State the problem:** We need to find the average speed of the Moon orbiting the Earth, given the orbit radius and the orbital period. 2. **Given data:** - Radius of orbit, $r = 384400$ km - Orbital period, $T = 27$ days 3. **Formula for average speed:** The average speed $v$ is the total distance traveled divided by the time taken. Since the orbit is circular, the distance traveled in one orbit is the circumference of the circle: $$\text{Distance} = 2\pi r$$ 4. **Convert time to hours:** $$T = 27 \text{ days} = 27 \times 24 = 648 \text{ hours}$$ 5. **Calculate the circumference:** $$2\pi r = 2 \times \pi \times 384400 \approx 2 \times 3.1416 \times 384400 = 2412619.4 \text{ km}$$ 6. **Calculate average speed:** $$v = \frac{\text{Distance}}{\text{Time}} = \frac{2412619.4}{648} \approx 3721.6 \text{ km/h}$$ 7. **Final answer:** The average speed of the Moon is approximately **3721.6 km/h** to 1 decimal place.