Frequency and wavelength are two variables which are
indirectly proportional.
They are related in the following equation:
f = c / w
Where,
f = frequency c =
speed of light w = wavelength
Since c is constant, we can equate condition 1 and
condition 2:
f1 w1 = f2 w2
When w2 = 3 w1, then f2 becomes:
261.63 w1 = f2 (3 w1)
Cancelling w1:
f2 = 261.63 / 3
f2 = 87.21 Hz
