[TYPO3-english] How to show a random news in list or last mode

[Taras Sajuk]

I have some news (tt_news), basically announcements of publication in the
future. They all have a start and a end date.
I want to show only one, but random, of the active news entries (start < now
< end) in LIST or LAST mode of the FE-plugin.

I have the feeling that the "listStartId" value is a good start, but how do
I get the total number of visible news and how can I set the "listStartId"
to a random value?

Taras Sajuk