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May 122014

Thanks to Ron Barrow for this helpful example of how to use probability tree diagrams. 158,411 views is impressive! You need to know this if you are taking the GCSE Higher paper.

This video by Luke Redding is also very clear and takes the topic a bit further because it includes experiments where the item is not replaced.

Maths is fun also explains this well and includes some interactive questions. GCSE Bitesize is another good site to test yourself on this.




Feb 072013

Here are some probability questions from Transum. If you get one wrong use your back button on your browser and try again.

Dec 032012

Here is a Roulette Simulator. It’s just as much fun as being in a casino, but it is completely free so you are not throwing away your money! Have a few goes and see how quickly you lose your money!

Why does the bank always win? Probability shows us that the odds are stacked against the gambler.

Let me explain.  Say we place a bet of £1 on Number 24. Assuming the roulette wheel is fair, there is one chance in 37 of this happening, because there are 37 different numbers on the roulette wheel. If you win, the bank pays you 35 times your bet. So if we do this 37 times we would expect to win once. We would lose £37 in bets and win back £36, so overall we lose £1!

A similar thing happens if you bet on pair (even) or impair (odd). Zero does not count as odd or even. So the probability of getting an even number is 18/37. The probability of an odd number is also 18/37. If you win the bank pays you the same amount as your bet. So if we play 37 times, each time betting £1, we would only expect to win 18 times. We would bet £37 and win £18 x 2 =£36, losing £1 overall.

Casinos make massive profits as they are always bound to win in the long run. True, very occasionally someone strikes lucky and has a big win, but the casino knows the odds are stacked in their favour.



Oct 052012

Download, print and cut out the triangles. Work with a friend to try and match all the questions with the correct answers and make a shape.

Probability Level 2 Jigsaw

Oct 052012

Download, print and cut out the triangles. Work with a friend to try and match all the questions with the correct answers and make a shape.

Probability Level 1 Jigsaw

Jul 062012

Download the pdf, print it and cut out the dominoes. Work with a friend to put them together correctly or play dominoes by sharing the dominoes and taking it in turns to place the next domino. If you can’t go the other player has another turn. The winner is the first to place all their dominoes correctly.

Download Simple Probability Jigsaw

If you have never played cards before here is a magician showing you what they look like

You need to understand there are four suits, spades♠, hearts♥, diamonds♦ and clubs♣.
Spades and clubs are black, hearts and diamonds are red. There are 13 cards in each suit, so altogether there are 4×13=52 cards in a pack. Number one is called an Ace. They are then numbered up to 10. After 10 there is a Jack, Queen and King.These are called picture cards.


Thanks to Mr Barton Maths for this Jigsaw.

If you are struggling you can view the solution here.
Simple Probability Solution

Mar 062012

Download this pdf, print and cut out the triangles. Try to arrange all the triangles so that the questions match with the answers. If you get it right you should make a new shape.

Download Probability Events Jigsaw

If you need a reminder of how to work out probabilities, try this link.


Thanks to Mr Barton for the original jigsaw.

If you are really stuck the solution is here.

Feb 112012

See how much money you can win on this addictive game! To calculate the probability each time work out first how many card are left and put this number on the bottom of the fraction. Then work out how many cards that haven’t been turned over yet are higher or lower than the last card. Put this number on the top.Sometimes you will be certain that the next card is higher or lower because all the cards that are higher have already been turned over. If you are certain then it is worth wagering all the money. If the probability is nearer to a half only gamble a small amount of money. This way you should soon become rich!