This is called a binomial distribution of probabilities, which occurs where there
are two possible outcomes (here a head or a tail). These probabilities may be
represented by a diagram in which both the heights and areas describe them.
The number of heads in four tosses of a coin, according to the binomial distribution
Tossing the coin four times is a bit restrictive. What happens if we throw it a
large number, say 100, times? The binomial distribution of probabilities can be
applied where n = 100, but it can usefully be approximated by the normal bell-
shaped curve with mean μ = 50 (as we would expect 50 heads when tossing a
coin 100 times) and variability (standard deviation) of σ = 5. This is what de
Moivre discovered in the 16th century.