Question

The frequency of the musical not B3 is about 246.94 Hz. What is the frequency of the note a perfect fifth below B3

370.42 Hz
246.94 Hz
241.94 Hz
164.63 Hz

Answer 1

Notes separated by a perfect fifth have a frequency ratio of 3:2.
The frequency of the note a perfect fifth below B3 will be
  246.94×2/3 = 164.62667

The appropriate choice is ...
  164.63 Hz

Answer 2

164.63Hz is the correct answer