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Probability
Serena Saliba
What is probability?
What is probability?
• Probability is a measure of how likely it is that some event will
occur.
Examples:
• The odds of winning Powerball are 1 in 55 million.
• There are 5 marbles in a bag: 4 are blue, and 1 is red. What is
the probability that a blue marble will be picked?
• It is certainly going to rain tomorrow.
Blaise Pascal and Probability
• Notions of probability have been around for
many thousands of years, however probability
as we know it, only became a mathematics
concept during the mid seventeenth century.
Blaise Pascal
• In 1654, a simple question was directed to Blaise Pascal and fellow
mathematician Pierre de Fermat, by a noble Frenchmen named Chevalier de
Méré.
• The question was in reference to a popular dice game.
• This particular game consisted of throwing a pair of dice twenty-four times.
• Méré was a frequent gambler. The main reason he
gambled was to increase his wealth.
Chevalier de Méré
• Méré bet on a roll of a die that at least one 6 would
appear during a total of four rolls. This approach
proved to be successful.
• In hope of making the game more interesting, he bet
that he would get a total of 12 or a double 6 on
twenty-four rolls of two dice.
• It didn’t take long for Méré to realise that his old approach to the game
was more prosperous.
• Mere consulted his friend, Blaise Pascal , and asked why his new approach
was not as profitable.
• Pascal found that the probability of winning using the new approach was
only 49.1% compared to 51.8% using the old approach.
Pierre de Fermat
• This problem started the famous collaboration
between Pascal and Pierre de Fermat.
• Pascal and Fermat continued to exchange their
thoughts on mathematical principles and
problems via letters.
• Historians think that the first letters written between Pascal and
Fermat were associated with Méré’s probability inquiry,
however this gradually evolved to include other problems
dealing with the aspiring probability theory.
• Pascal and Fermat are the mathematicians who are recognised
as establishing the theory of probability as we know it today.