How to get python to generate random size?

I need to make my python code draw my stars in different sizes at random. I've tried every method I know but unable to figure it out...still trying to completely understand loops.

 import turtle
 import random

for n in range(60):
turtle.penup()
turtle.goto(random.randint(-400, 400), random.randint(-400, 400))
turtle.pendown()

red_amount   = random.randint( 0,  100) / 100.0
blue_amount  = random.randint(0 , 100) / 100.0
green_amount = random.randint( 0,  100) / 100.0
turtle.pencolor((red_amount, green_amount, blue_amount))

turtle.pensize(random.randint(1, 10))

for i in range(6):
    turtle.begin_fill()
    turtle.forward(50)
    turtle.right(144)
    turtle.end_fill()

All it does currently is draw stars at the same size.