Maths

Probability - Introduction

This is an introduction to probability. This subject is really very easy if you get to grips with it.
It really is to do with chances. You can say, "What is the chance that something will happen?" This is the same as, "What is the probability of something happening?"
It's the same thing really!
Today we are going to introduce the concept of probability and get you used to the language.

The probability (chance) of something happening starts at one extreme (won't happen) and ends at another (will happen).
This means that the chance of something happening can be either: impossible, certain or somewhere in-between.

If it might happen it could be unlikely, an even chance or likely Here are a few examples

What is the probability that you will go to sleep tonight? Where would you put a mark on the diagram above?

Will happen

What is the chance of tossing a head or tail on a one pence piece? Where would you put your mark on the line above?

Even chance.

Let us look at a more difficult idea.

What is the probability that you will draw a red card out of a normal pack of cards with no jokers?

Well you have to know how many cards there are in a normal pack (52)
You have to know how many cards are red (26)

Now you can work out the chance of getting a red card

26 out of 52 or
an even chance since 26/52 = 1/2.

This is the basic idea of probability:
How many are there in total and what is your chance of getting your choice?

We will build on this brief introduction next time we look at probability.

To finish off:

Here are a couple of questions for you to check your understanding of what you have done so far.

I HAVE GOT 4 RED BALLS 4 GREEN BALLS AND 2 WHITE BALLS IN A BAG.
WHAT IS THE PROBABILITY THAT I CAN PICK A WHITE BALL OUT OF THE BAG?

2 out of ten or 2/10, which equals 1/5
Ten balls in total and 2 of them are white.
Is this likely, even or unlikely?