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## Grades 8 to 10 At least one

*By toni On 12 November, 2016 · Leave a Comment*

If Busi has 3 children what is the probability that at least one will be a girl?

Imagine tossing a coin three times.

What’s the probability you will get a head on at least one of the tosses?

Suppose you drew this tree diagram. How would it help you to find the answers to […]

## Grades 9 to 12 Mathsland Lottery

*By toni On 11 August, 2016 · Leave a Comment*

In the Mathsland Lottery, 49 balls are numbered 1 to 49 and 6 balls are chosen at random without replacing any of the balls so that 6 different winning numbers are chosen.

Each lottery ticket has 6 numbers and you win a top prize if your 6 numbers match theĀ 6 numbers chosen that […]

## Grades 9 to 12 Lucky Numbers

*By toni On 11 August, 2016 · Leave a Comment*

In the Lucky Numbers Game 6 balls are numbered 1 to 6 and 3 balls are chosen at random without replacing any of the balls so that 3 different winning numbers are chosen.

When you play this game you get a ticket with 3 numbers written on it.

You win a prize if […]

Two dice are RED and one is GREEN.

Roll the dice and add up the numbers on the two RED dice and then subtract the number on the GREEN.

So if one RED is 4 and the other RED is 5 and the GREEN is 3 we should add together 4 and 5 to […]

## Grades 5 to 12 In a Box

*By toni On 20 August, 2013 · 37 Comments*

Najwa and Zuki play a game.

They put two red and two blue ribbons in a box. They pull out two ribbons at the same time without looking at the colours.

Najwa wins if both ribbons are the same colour.

Zuki wins if the two ribbons are different colours.

Is this a fair […]

## Grades 10 to 12 Out in the Snow

*By toni On 15 August, 2013 · Leave a Comment*

A motorist plans to drive to Cradock. Event X is that he arrives at his destination in less than 3 hours. He estimates that the probability of it snowing is 1/6 and the probability of event X if it snowed is 1/10.

What is the probability that it snows and he gets there in […]

## Grades 9 to 12 Odds and Evens

*By toni On 29 January, 2013 · Leave a Comment*

In Game A you pick out two balls at random from a bag containing balls numbered 2, 3, 4, 5 and 6.. If the total is even you win. If it is odd you lose. Are you equally likely to win or to lose (a fair game)?

## Grades 7 to 10 Nines and Tens

*By toni On 19 March, 2012 · 24 Comments*

Both 9 and 10 can be made up in 2 different ways by adding pairs of the numbers 1, 2, … 6, that is

9 = 3 + 6 = 4 + 5

10 = 4 + 6 = 5 + 5

Explain why it is that when you throw two dice you are more […]

## Grade 9 to 12 – Two’s Company

*By toni On 19 March, 2012 · 2 Comments*

A container holds 4 yellow balls, 2 blue balls and a red ball. The balls are identical in all ways except colour. When you shake the container the balls settle into a hexagonal pattern as shown in the diagram.

You win if two blue balls touch.

How many different ways can […]

## Grades 11 and 12 Same Birthday

*By toni On 17 February, 2012 · 10 Comments*

In a group of 23 people there is more than a 50% chance that two will have the same birthday? Does that surprise you?

Including February 29th how many different birthdays can there be? Start with any 3 people A, B and C. What is the probability that B has a different birthday from […]

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