0.03s
Explanation:
Period of wave and its frequency are closely related. Period is the inverse of frequency.
The period of a wave is the time taken for a number of waves to pass through a particular point.
The frequency of a wave is the number of waves that passes through a point at a particular time.
So;
     f  =
Â
f is the frequency
T is the period
  Period of the wave  =
 = 0.03s