from random import random

a = 0.5
b = 1.5
n = 1000

meanX = 0
for sampleNumber in range(1000):
    x = 1
    for i in range(n):
        if random() <= 0.5:
          x *= a
        else:
          x *= b
    meanX += x
    
print (meanX / 1000)