(a) Is the beat frequency produced when a 245-Hz tone and a 240-Hz tone are played together greater than, less than, or equal to the beat frequency produced when a 140-Hz tone and a 145-Hz tone are played together?
(b) Choose the best explanation from among the following:
I. The beat frequency is determined by the difference in frequencies and is independent of their actual values.
II. The higher frequencies will produce a higher beat frequency.
III. The percentage change in frequency for 240 and 245 Hz is less than for 140 and 145 Hz, resulting in a lower beat frequency.