Answer
3.91 ms. 1.33 m.
Work Step by Step
a. Period $T = \frac{1}{f} = \frac{1}{256 Hz} = 0.00391 s = 3.91 ms $.
b. The wave speed is frequency multiplied by wavelength.
$v = 340 \frac{m}{s} = f \lambda = (256 Hz)(\lambda )$.
Solve for $\lambda = \frac{340 m/s}{256 Hz} = 1.33 m$.
Alternatively, for part b, use $d = vt = (340 \frac{m}{s})(\frac{1}{256} s) = 1.33 m$.