Tuesday, 3 March 2009

Probability for heads and tails

Heads or tails is fairly easy. What are the chances of Chelsea winning the premiership? Well the bookies may have some odds for you but it depends on how well they do as compared to all the other teams in the league. You can have a guess or even a good idea, especially as we get closer to the end of the season, but in maths some aspects of chance are much easier to evaluate. Weighing up the chances in maths is called probability.

Take a coin and toss it. Does it land on heads or tails? As long as the coin is not weighted there should be an equal chance of it landing on heads or tails. If there is going to be any cheating you don't usually think of a weighted coin. You can have weighted dice but let's not get involved in complex maths just yet.

What are the chances of the coin landing on heads? Well the answer is one in two. What are the chances of it landing on heads twice? It is the same odds the next time you toss the coin. To get heads twice the odds are 1/2 x 1/2 = 1/4. If you tossed the coin twice and did this lots of times then you will roughly have a quarter heads and heads, a quarter tails and tails, and half will have one tails and one heads, because you could have a heads then a tails, or a tails then a heads.

That sums it up

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