KS2 probability

Table of Contents


 Unit 1 | Algebra

Page 1 | Expressions and Formulae

Page 2 | Index notation

Page 3| Solving Linear Equations

Page 4| Expanding and Factorising

Page 5| Factorising Quadratics and expanding double brackets

Page 6| Patterns and Sequences

Page 7| Simultaneous Equations

Page 8| Changing the subject of a Formula

Page 9| Adding , subtracting algebraic formulas

 Unit 2 |Graphs

Page 1 | Straight line graphs

Page 2 | Graphs of Quadratic functions

Unit 3 |Geometry and Measure

Page 1 | Transformations

Page 2 | Symmetry

Page 3 | Coordinates

Page 4 | Perimeter, Area, Volume

Page 5 | Circle geometry

Page 6 | Measurement

Page 7 | Trigonometry

Page 8 | Pythagoras

Page 9 | Angles

Page 10 | Shapes

Page 11| Time

Page 12 | Locus

Unit 4 | Numbers

Page 1 | Speed, Distance and time

Page 2 | Rounding and estimating

Page 3 | Ratio and proportion

Page 4 | Factors, Multiples and primes

Page 5 | Powers and roots

Page 6 | Decimals

Page 7 | Positive and negative numbers

Page 8 | Basic operations

Page 9 | Fractions

Page 10 | Percentages

Unit 5 | Statistics and Probability

Page 1 | Sampling data (MA)

Page 2 | Recording and representing data

Page 3 | Mean median range and mode

Page 4 | Standard deviation

Unit 4 | Calculus


We use probability to figure out how likely it is that something will happen. For example, for people who live in Britain, it is very likely that it will rain in September. But it you live in the middle of the Sahara Desert, it is very unlikely that it will rain in September (or any other time of year!).

Many events will have more than one outcome – if you roll a dice, it could land on 1, 2, 3, 4, 5 or 6 – so we use probability to help us guess which outcome is going to happen.

If there is an equally likely chance of things happening, then we say that there is an even chance.

We can use words and fractions to show the probability of something happening.  However, if we’re writing probability as a fraction, it’s important to remember that these probabilities can only be between 0 and 1. 0 is impossible and 1 is certain and we can’t have a chance that something is going to happen as less than impossible or more than certain.  An even chance of two things happening is written as ½ .

Example 1:

If we use our dice example again, we can show words and fractions can be used to show probability.  Let’s say that we want to find out the probability of rolling a two.

There are six possible outcomes of rolling a dice – that it will land on 1, 2, 3, 4, 5 or 6 – and there’s only one of these outcomes that we can roll two. So, the probability of rolling a two is 1 in 6.

If we want to write this as a fraction, the number of possible outcomes becomes the denominator and the number of ways to get the outcome we want is the numerator. So, as a fraction, the probability of rolling a two is  .

Therefore, when trying to find probability as a fraction, you must first find all the different outcomes that could possibly happen, and then find how many of those different outcomes are the outcome that you are trying to find.





2) A box contains 20 green counters. How many blue counters must be added to the box so theres an equal chance of picking a green counter?box

3) Sajid is making a gane.He has marked some number on a spinner .

a) Using only the letters P and F, Write in the empty section so theres a greater chance of landing on a F than a P.

p-f-boxb) Sajid has made another spinner ,Sajid think there a greater chance of landing of landing on a P than F.is he correct?

Explain why?


4) Gulam has sacks of potatoes. The probability of selecting a rotten potato from sake A is 3/10.

potatoes-a potatoes-b

a) Mark on the scale ,the probability of selecting a potato from sack b.


b) How many rotten potatoes should be added to sack C in order for the probability of selecting a rotten potato equals 1/3 =box


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