Resources tagged with: Conditional probability

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There are 26 NRICH Mathematical resources connected to Conditional probability, you may find related items under Probability.

Broad Topics > Probability > Conditional probability

The Birthday Bet

Age 14 to 16
Challenge Level

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 ?

Two's Company

Age 11 to 14
Challenge Level

Seven balls are shaken. You win if the two blue balls end up touching. What is the probability of winning?

Put Out

Age 16 to 18
Challenge Level

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?

In a Box

Age 14 to 16
Challenge Level

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?

Snooker Frames

Age 16 to 18
Challenge Level

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?

Rain or Shine

Age 16 to 18
Challenge Level

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.

Do You Brush Your Teeth Every Day?

Age 14 to 18
Challenge Level

How can we find out answers to questions like this if people often lie?

Dropouts

Age 14 to 16 Short
Challenge Level

What percentage of students who graduate have never been to France?

Winning Marble

Age 14 to 16 Short
Challenge Level

How can this prisoner escape?

Statins and Risk

Age 14 to 16
Challenge Level

"Statins cut the risks of heart attacks and strokes by 40%"
Should the Professor take statins? Can you help him decide?

How Risky Is My Diet?

Age 11 to 16
Challenge Level

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

Non-transitive Dice

Age 11 to 14
Challenge Level

Alison and Charlie are playing a game. Charlie wants to go first so Alison lets him. Was that such a good idea?

Drug Testing

Age 16 to 18
Challenge Level

How do different drug-testing regimes affect the risks and payoffs for an athlete who chooses to take drugs?

Ante Up

Age 16 to 18
Challenge Level

Use cunning to work out a strategy to win this game.

At Least One...

Age 11 to 14
Challenge Level

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?

Mathsland National Lottery

Age 14 to 16
Challenge Level

Can you work out the probability of winning the Mathsland National Lottery?

Same Number!

Age 14 to 16
Challenge Level

If everyone in your class picked a number from 1 to 225, do you think any two people would pick the same number?

Dicey Dice

Age 16 to 18
Challenge Level

Invent a set of three dice where each one is better than one of the others?

X-dice

Age 16 to 18
Challenge Level

Explore these X-dice with numbers other than 1 to 6 on their faces. Which one is best?

Succession in Randomia

Age 16 to 18
Challenge Level

By tossing a coin one of three princes is chosen to be the next King of Randomia. Does each prince have an equal chance of taking the throne?

Master Minding

Age 11 to 14
Challenge Level

Your partner chooses two beads and places them side by side behind a screen. What is the minimum number of guesses you would need to be sure of guessing the two beads and their positions?

Penta Colour

Age 14 to 16
Challenge Level

In how many different ways can I colour the five edges of a pentagon red, blue and green so that no two adjacent edges are the same colour?

Fixing the Odds

Age 14 to 16
Challenge Level

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. . . .

Coin Tossing Games

Age 14 to 16
Challenge Level

You and I play a game involving successive throws of a fair coin. Suppose I pick HH and you pick TH. The coin is thrown repeatedly until we see either two heads in a row (I win) or a tail followed by. . . .

Snooker

Age 16 to 18
Challenge Level

A player has probability 0.4 of winning a single game. What is his probability of winning a 'best of 15 games' tournament?

Squash

Age 16 to 18
Challenge Level

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?