The pyrene/coumarin FRET pair (r 0 = 39 ) is used to study the fluctuations in enzyme

The pyrene/coumarin FRET pair (r₀ = 39 Å) is used to study the fluctuations in enzyme structure during the course of a reaction. Computational studies suggest that the pair will be separated by 35 Å in one conformation, and 46 Å in a second configuration. What is the expected difference in FRET efficiency between these two conformational states?