5 seconds
Step-by-step explanationA wave is a disturbance in a medium that carries energy without a net movement of particles, the frequency is the number of waves that pass a fixed point in unit time
it is written as:

and the wave period is the time it takes to complete one cycle ,it is inversely proportional to the frequency of a wave, we can find the period using the formula

Step 1
given:

now, replace in the formula

therefore, the Period is 5 seconds
I hope this helps you