conditional/probability practice

mySketch
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//when mouse is pressed, usually a square, sometimes a circle appears
void setup()
{
  size(600,600);
  background(0);
}
​
void draw()
{
   if(mousePressed)
    {
      if(random(100)<80)
        {
          fill(random(20,255),random(20,255),random(20,255));
            rect(mouseX,mouseY,20,20);     
        }
        else
        {
          fill(random(20,255),random(20,255),random(20,255));
            ellipse(mouseX,mouseY,20,20);     
        }
    }
​
}