Help with simple Adsense rotator (80%/20%) please

[gemini181]

I have various 'code snippets' which rotate photos, pick random numbers, ect.
This is something I can figure out, but I'm looking for a quick simple solution (without using PHPadsNew, for example)
~~~~~~~~~~~~
All I need is

• 'sharerev.php' (for example) which contains only the Adsense code for a writer, mod, or admin.
• ...and 'myrev.php' which has only my Google ad code
• Now I need a flexable, easy way to 'give 80%' to sharing
• and have mine appear ~20% of the time

I'm 'OK' at modifying code, and just starting to learn to actually write.
Please, give a 'basic framework' for randomly having one PHP file called on ~80% of the time, and just some ideas on a simple, basic 'actual usage example.'

Thank you very much.

[kromey]

$prob = 80; //probability of showing your first one
$rand = mr_rand(1,100); //random probability
if($rand < $prob)
    include("inc1.php"); //will show up $prob percent of the time
else
    include("inc2.php"); 

[gemini181]

Much better than what I found searching in Google!

Thank you so much

[kromey]

Woot! I trumped Google!!