Array problem

Ok I have an array with folowing values
$x=array(a=>34,b=>32,c=>31,d=>29,e=>28,f=>24,g=>21...,z=>1)
so a descending values in an array

now I would like to make this array shorter like:
$x=array(a=>34,b=>32,c=>31)
(only first 3 values)

and than randomize it:
$x=array(c=>31,a=>34,b=>32) or something like that (random...)

How can I do this ?

 

http://www.php.net/array-chunk
http://www.php.net/shuffle

 

thank you