Give that the frequency of G5 is 783.99 Hz.
To find the frequency of the note that is a perfect fifth above G5, we recall that the frequencies of notes that are a 'perfect' fifth apart are in the ratio of 1.5
i.e. the frequency of the note that is a perfect fifth above G5 divided by the frequency of G5 equal 1.5
Let the frequency of the note that is a perfect fifth above G5 be F, then
F / 783.99 = 1.5
F = 1.5 x 783.99 = 1175.99
Therefore, the frequency of the note that is a perfect fifth above G5 is 1175.99 Hz