Conditional probability

There are 26 NRICH Mathematical resources connected to Conditional probability
Non-Transitive Dice
problem
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Non-transitive dice

Age
11 to 14
Challenge level
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Alison and Charlie are playing a game. Charlie wants to go first so Alison lets him. Was that such a good idea?
Same Number!
problem
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Same number!

Age
14 to 16
Challenge level
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If everyone in your class picked a number from 1 to 225, do you think any two people would pick the same number?
Rain or Shine
problem
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Rain or shine

Age
16 to 18
Challenge level
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Predict future weather using the probability that tomorrow is wet given today is wet and the probability that tomorrow is wet given that today is dry.
Mathsland National Lottery
problem
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Mathsland national lottery

Age
14 to 16
Challenge level
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Can you work out the probability of winning the Mathsland National Lottery?
At least one...
problem
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At least one...

Age
11 to 14
Challenge level
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Imagine flipping a coin a number of times. Can you work out the probability you will get a head on at least one of the flips?

Snooker Frames
problem
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Snooker frames

Age
16 to 18
Challenge level
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It is believed that weaker snooker players have a better chance of winning matches over eleven frames (i.e. first to win 6 frames) than they do over fifteen frames. Is this true?
In a box
problem
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In a box

Age
14 to 16
Challenge level
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Chris and Jo put two red and four blue ribbons in a box. They each pick a ribbon from the box without looking. Jo wins if the two ribbons are the same colour. Is the game fair?
Put Out
problem
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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?
Two's company
problem
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Two's company

Age
11 to 14
Challenge level
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Seven balls are shaken. You win if the two blue balls end up touching. What is the probability of winning?
The Birthday Bet
problem
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The birthday bet

Age
14 to 16
Challenge level
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The next ten people coming into a store will be asked their birthday. If the prize is £20, would you bet £1 that two of these ten people will have the same birthday ?