Frequency Trees Flashcards

All 6 cards in this deck

What is a frequency tree?

A diagram showing how a total splits into groups at each stage, with the frequency (a whole number) written in each circle.

In a frequency tree, what must a pair of branch numbers coming from the same point add up to?

The frequency they came from.

e.g. $22$ males split into $18$ right-handed and $4$ left-handed

What are the steps to complete a frequency tree?

e.g. 50 people, 30 are male, 12 of the males passed

1. Fill in the first pair of branches: $50-30=20$ females
2. Use each given value to find its partner: $30-12=18$ males failed
3. Check every pair adds to the number before it

Using a completed frequency tree, how do you find the probability that an adult chosen at random passed?

Number of adults who passed $\div$ total number of adults.

e.g. $\frac{20}{32}$

On a frequency tree, how do you find the total number who passed altogether?

Add the 'passed' frequencies from every branch.

e.g. $20$ adults $+\ 34$ children $=54$

True or false? You should write probabilities on the branches of a frequency tree.

False. A frequency tree is completed with frequencies (whole numbers); using probabilities loses marks.