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Edexcel A-Level Mathematics A2 S3.4.2 Degrees of Freedom Questions

Practise degrees of freedom in chi-squared tests by choosing v for contingency tables, fitted models and combined frequency classes.

Syllabus
First assessment 2019
Course
Mathematics YMA01
Level
A2

Exam points

  • Use (rows−1)(columns−1) for contingency tables before choosing the χ² critical value.
  • Reduce degrees of freedom when parameters are estimated or categories are combined.

Edexcel A-Level Mathematics A2 S3.4.2 Degrees of Freedom Questions question 1

[Maximum number: 4]

A research student is investigating the number of children who are girls in families with 4 children.

The table below shows her results for 200 such families.

Table for Question Edexcel A-Level Mathematics A2 S3.4.2 Degrees of Freedom Questions question 1 — Edexcel A-Level Mathematics A2

The research student suggests that a binomial distribution with p=12p=\frac{1}{2} could be a suitable model for the number of children who are girls in a family of 4 children.

Test, at the 5% significance level, whether using a binomial distribution is suitable to model the number of children who are girls in a family of 4 children.
You should state your hypotheses and the critical value used.

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