What is the modulation index of an FM phone signal having a maximum carrier deviation of plus or minus 6 kHz if the highest modulating frequency is 2 kHz?

Explication

Both quantities are in the same units, so divide directly: 6 kHz ÷ 2 kHz = 3, the plus-or-minus figure already being the peak swing on each side. As in E8B03, what is actually supplied is a maximum deviation and a highest modulating frequency — the pool's own definition of deviation ratio in E8B09 — so the label differs from the one in the question while the computation does not.