G'day,
OK, here's the maths:

CD quality is 44100 samples per sec in each channel. Each sample is 2 bytes. Stereo: 2 channels.

44100 x 2 x 2 = 176400 bytes / sec.

176400 x 60 = 10,584,000 bytes / min

1 MB = 1024 x 1024 bytes, i.e. 10,584,000 bytes = 10.093688 MB. Close enough to 10MB / min.

At 22.05 kHz Stereo 5MB / min

650 MB on a CD ROM / 5 = 130 min

So that's about 50 Beatles songs or 25 folk songs

Double that if they're mono. Still a long way short of getting the entire collection on 1 CD ROM.

I reduced my complete collection of Beatles CDs down to 6 CDs containing 161 songs. That's about 3/4 of their total. If I had done that at 22kHz it still would have taken 3 CDs (except that's not a valid audio CD format). Also note that audio CDs have a capacity of 740 MB, not 650 MB. So I've used 6 x 740 MB. Divide by 2 for 22kHz and I'd need 3.4 CD ROMs, which of course means 4. More for the entire collection. Halve all that for mono.

Cheers,
Alan