Grade 7 Math · Statistics & Probability

Represent compound events with tree diagrams

Represent compound events with tree diagrams.

Practice more with MathNivoAndroid app coming soonExplore the idea here, then continue practicing in the Android app when available.

What you’ll learn

Represent compound events with tree diagrams.

Key idea

Alternative first branches contribute separate groups of terminal paths; groups add, unlike consecutive stage choices.

Alternative branch groups add; a complete path does not traverse both alternatives.

Worked example

Enter the exact value or ordered values in the format requested below.

Two-stage tree: Start→R→['R1', 'R2', 'R3']; Start→B→['B1', 'B2', 'B3', 'B4', 'B5']. Enter its total terminal leaves.

  1. The first-stage alternative R leads to 3 leaves, while alternative B leads to 5 leaves.
  2. A full path takes either R or B, not both; total=3+5=8, and missing B count=8-3=5.

Answer: 8

Quick Check

Evaluate a worked attempt at represent compound events with tree diagrams, identify the first invalid step, and provide the correction.

Tree Start→R→['R1'], Start→B→['B1', 'B2', 'B3', 'B4', 'B5', 'B6']. Step1 counts 1 R leaves and 6 B leaves. Step2 multiplies groups to claim 6 full paths. Locate the first invalid step and correct the total.

Choose one answer

Show a hint

Count full paths ending in leaves rather than branch labels alone.