In [1]:
p_en = {
  'e': 0.12702,
  't': 0.09056,
  'a': 0.08167,
  'o': 0.07507,
  'i': 0.06966,
  'n': 0.06749,
  's': 0.06327,
  'h': 0.06094,
  'r': 0.05987,
  'd': 0.04253,
  'l': 0.04025,
  'c': 0.02782,
  'u': 0.02758,
  'b': 0.01492
  # more
}

p_de = {
  'e': 0.16396,
  'n': 0.09776,
  's': 0.07270,
  'r': 0.07003,
  'i': 0.06550,
  'a': 0.06516,
  't': 0.06154,
  'd': 0.04577,
  'h': 0.04577,
  'u': 0.04166,
  'l': 0.03437,
  'b': 0.01886
  # more
}

def p_text(text, dist):
    prod = 1.0
    for letter in text:
        prod *= dist[letter]
    return prod
In [4]:
ll_de = p_text('rhabarber', p_de)
ll_de
Out[4]:
3.892393415255438e-12
In [5]:
ll_en = p_text('rhabarber', p_en)
ll_en
Out[5]:
2.466408964234113e-12
In [6]:
ll_de * 0.7 / (ll_de *0.7 + ll_en*0.3)
Out[6]:
0.7864333258300723