5 m/s 8 m/s 12 m/s 20 m/s
I gave my students this multiple choice question: What is the speed of a 2-Hz wave that has a wavelength of 10 m?

Only one answer is correct among these 4 choices:
- 5 m/s
- 8 m/s
- 12 m/s
- 20 m/s

Could you tell me which one is correct?

20 m/s