1.1.11

Number of Combinations

Test yourself

Number of Possible Combinations

To count the number of possible combinations, work out how many possible options there are for the first part, then work out the number of options for the second part. Then multiply the numbers together.

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Parts in a play - question

  • There are 3 parts in a play.
  • 10 boys are auditioning for both the 1st and 2nd parts and 7 girls are auditioning for the 3rd part.
  • How many possible casts are there?
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Parts in a play - solution

  • 10 possible choices for first part (all 10 boys)
  • 9 choices for second part (all 10 boys except the one who got the 1st part)
  • 7 choices for third part
  • So 10 × 9 × 7 = 630 combinations in total.

Jump to other topics

1Number

1.1Using Numbers

1.2Fractions, Decimals & Percentages

1.3Powers & Roots

1.4Accuracy

2Algebra

2.1Introduction to Algebra

2.2Manipulating Algebra

2.3Proofs & Functions

2.4Straight Line Graphs

2.5Common Graphs

2.6Transformations & Tangents

2.7Properties of Graphs

2.8Solving Equations

2.9Inequalities

2.10Sequences

3Ratio

4Geometry

4.1Introduction to Geometry

4.2Triangles & Quadrilaterals

4.3Transformations

4.4Circle Basics

4.5Circle Theorems

4.6Measurements & Units

4.7Calculating Area

4.8Triangle Formulae

4.93D Shapes

4.10Vectors

5Probability

6Statistics

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