Answer
$v=1.97\times 10^8\frac{m}{s}$
Work Step by Step
We know that velocity, frequency and wavelength are linked by the formula,
$v=f \lambda$
We plug in the known values in the formula above to obtain:
$v=5.09\times 10^{14}\times 388\times 10^{-9}$
$v=1.97\times 10^8\frac{m}{s}$
