from random import *

def Distance():
    e=70
    x=0
    for k in range(100):
        a=random()
        if a<=0.7:
            x=x+1
    d=abs(x-e)
    return d

def Echantillon(n):
    s=4.58
    y=0
    for j in range(n):
        if Distance()>=2*s:
            y=y+1
    p=y/n
    return p