**"Tree diagrams"**

## 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 […]

## Grades 8 to 10 Same Birth-month

*By toni On 17 February, 2012 · 8 Comments*

The probability that there are two people in a group with birthdays in the same month depends on the size of the group.

What if the group has more than twelve people?

What about a group of 2 people? What is the probability they have birthdays in different months?

## Grades 9 to 11 – How Many Factors?

*By toni On 18 January, 2012 · 3 Comments*

What can you say about numbers that have exactly 2 factors?

What can you say about numbers that have exactly 3 factors?

Give some examples of numbers with 4 factors. What do they have in common?

Give some examples of numbers with 5 factors. What do they have in common?

What about numbers […]

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