Combining probabilities

There are 23 NRICH Mathematical resources connected to Combining probabilities
Fixing the Odds
problem

Fixing the odds

Age
14 to 16
Challenge level
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You have two bags, four red balls and four white balls. You must put all the balls in the bags although you are allowed to have one bag empty. How should you distribute the balls between the two bags so as to make the probability of choosing a red ball as small as possible and what will the probability be in that case?
Voting Paradox
problem

Voting paradox

Age
14 to 18
Challenge level
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Some relationships are transitive, such as `if A>B and B>C then it follows that A>C', but some are not. In a voting system, if A beats B and B beats C should we expect A to beat C?
Taking Chances
problem

Taking chances

Age
11 to 14
Challenge level
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This article, for students and teachers, is mainly about probability, the mathematical way of looking at random chance and is a shorter version of Taking Chances Extended.
Heavy hydrocarbons
problem

Heavy hydrocarbons

Age
14 to 18
Challenge level
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Explore the distribution of molecular masses for various hydrocarbons
Molecular sequencer
problem

Molecular sequencer

Age
14 to 18
Challenge level
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Investigate the molecular masses in this sequence of molecules and deduce which molecule has been analysed in the mass spectrometer.
Dicey Decisions
problem

Dicey decisions

Age
16 to 18
Challenge level
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Can you devise a fair scoring system when dice land edge-up or corner-up?
Squash
problem

Squash

Age
16 to 18
Challenge level
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If the score is 8-8 do I have more chance of winning if the winner is the first to reach 9 points or the first to reach 10 points?
Snooker
problem

Snooker

Age
16 to 18
Challenge level
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A player has probability 0.4 of winning a single game. What is his probability of winning a 'best of 15 games' tournament?
Chance Combinations
problem

Chance combinations

Age
11 to 14
Challenge level
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Can you design a bingo board that gives you the best chance of winning?
How Risky \is my diet?
problem

How risky is my diet?

Age
11 to 16
Challenge level
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Newspapers said that eating a bacon sandwich every day raises the risk of bowel cancer by 20%. Should you be concerned?