Two progressive waves with frequency $300\,\text{Hz}$ combine to form a stationary wave, and neighbouring nodes are separated by $1.5\,\text{m}$. What is the speed of the progressive waves?
- A$100\,\text{m s}^{-1}$
- B$200\,\text{m s}^{-1}$
- C$450\,\text{m s}^{-1}$
- D$900\,\text{m s}^{-1}$