There are a lot of factors that go into calculating how long a presentation
will last.
First, will anyone be speaking, or does the show run by itself?
If you have a speaker, how fast will they be speaking?
Are they funny? How long will the laughter take?
Have you timed their presentation with a stopwatch?
Are there places where the audience has to interact with the speaker?
How long will you plan for this?
If the show runs by itself, without a speaker, start the slideshow & a
stop watch at the same time.
A presentation is much more than a slide show, which are you giving?
Bill Dilworth