Probability

There are 124 NRICH Mathematical resources connected to Probability
Odds or Sixes?
problem

Odds or Sixes?

Age
7 to 11
Challenge level
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Play this dice game yourself. How could you make it fair?
Two and One
problem

Two and One

Age
5 to 7
Challenge level
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Terry and Ali are playing a game with three balls. Is it fair that Terry wins when the middle ball is red?
The Twelve Pointed Star Game
problem

The Twelve Pointed Star Game

Age
7 to 11
Challenge level
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Have a go at this game which involves throwing two dice and adding their totals. Where should you place your counters to be more likely to win?
You Never Get a Six
problem

You Never Get a Six

Age
7 to 11
Challenge level
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Charlie thinks that a six comes up less often than the other numbers on the dice. Have a look at the results of the test his class did to see if he was right.
FA Cup
problem

FA Cup

Age
16 to 18
Challenge level
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In four years 2001 to 2004 Arsenal have been drawn against Chelsea in the FA cup and have beaten Chelsea every time. What was the probability of this? Lots of fractions in the calculations!
Limiting Probabilities
problem

Limiting Probabilities

Age
16 to 18
Challenge level
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Given probabilities of taking paths in a graph from each node, use matrix multiplication to find the probability of going from one vertex to another in 2 stages, or 3, or 4 or even 100.
Tricky Track
problem

Tricky Track

Age
7 to 11
Challenge level
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In this game you throw two dice and find their total, then move the appropriate counter to the right. Which counter reaches the purple box first?
Put Out
problem

Put Out

Age
16 to 18
Challenge level
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After transferring balls back and forth between two bags the probability of selecting a green ball from bag 2 is 3/5. How many green balls were in bag 2 at the outset?
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?
How Many Balls?
problem

How Many Balls?

Age
16 to 18
Challenge level
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A bag contains red and blue balls. You are told the probabilities of drawing certain combinations of balls. Find how many red and how many blue balls there are in the bag.