Poisson or Binomial distribution
• If a mean or average probability of an event happening per unit time/per page/per mile cycled etc.,
is given, and you are asked to calculate a probability of n events happening in a given
time/number of pages/number of miles cycled, then the Poisson Distribution is used.
• If, on the other hand, an exact probability of an event happening is given, or implied, in the
question, and you are asked to caclulate the probability of this event happening k times out of n,
then the Binomial Distribution must be used.