A wave traveling in water has a frequency of 250 Hz and a wavelength of 6.0 m. What is the speed of the wave?

Since you are looking for the speed, you need to rearrange the formula which is f = speed / wavelength. That should give you speed = f (wavelength.) All you need to do next is to substitute the value to the following equation. speed = 250 Hz (6.0m) that should leave you with 1500 m/s which is very fast.