(HAVRILIAK) writes:

Here is my result: 8 heads, twelve tails.

You have a biased coin

You cannot make that conclusion since, even with a fair coin, there is
a reasonably high probability of obtaining that result or worse. With
20 tosses the probabilities of obtaining 0 to 20 heads (or tails) can
be calculated from the binomial distribution and is as follows:

Heads Probability
0 0.00000095
1 0.00001907
2 0.00018120
3 0.00108719
4 0.00462055
5 0.01478577
6 0.03696442
7 0.07392883
8 0.12013435
9 0.16017914
10 0.17619705
11 0.16017914
12 0.12013435
13 0.07392883
14 0.03696442
15 0.01478577
16 0.00462055
17 0.00108719
18 0.00018120
19 0.00001907
20 0.00000095

So, the probability of getting exactly 10 heads is just 0.176 and to
get something else is 1-0.176 = 0.824, even with a perfectly fair
coin.

pej
--
Per Erik Jorde