怎么控制概率？思路如何?
我想这样的，一个转盘分成4块，可是怎么控制他们的概率不一样呢？要怎么写？

想不下去啊。。。。。求指引~chance为概率

$lottery_arr=array(

	"0"=>array("id"=>1,"min"=>0,"max"=>90,"chance"=>10),

	"1"=>array("id"=>2,"min"=>90,"max"=>180,"chance"=>20),

	"2"=>array("id"=>3,"min"=>180,"max"=>270,"chance"=>30),

	"3"=>array("id"=>4,"min"=>270,"max"=>360,"chance"=>40),

	)

------解决方案--------------------
http://denghai260.blog.163.com/blog/static/7268640920128244332285/
这个能实现你的要求