If waves on the lake have a frequency of 3 hertz and a wavelength of 4 meters, what is the speed of the waves?

You have to use the equation v=λf
v is the velocity of the wave
λ is the wave length of the wave (how far the wave goes in one cycle)
f is the frequency of the wave (how long one cycle is) 

V=4m×3Hz
v=12m/s

Hz stands for s⁻¹ which is why the final units is m/s

I hope this helps.  Let me know if anything is unclear.

Hello thereone of the following properties was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version. which property fits this description? answer: atomic mass  was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.