# WST03/01 June 2019

> WST03/01 June 2019: 8 questions, 75 marks. Difficulty 0.42, deviation 0.17, algebraic 0.40, text density 0.48. Edexcel IAL Mathematics S3.

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Edexcel IAL · Mathematics · 2019 June

This Statistics 3 (WST03) paper contains 8 questions worth 75 marks. The profile below reports five mark-weighted difficulty and complexity measures, and every question row repeats them. Full question text and mark scheme open in the Interactive Practice Hub.

- Edexcel IAL
- S3
- 8 questions
- 75 marks
- Free paper
- [Practise this paper](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e)
- [All S3 papers](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/)

Core finding

**WST03/01 June 2019 is a past paper for Edexcel IAL Statistics 3 (WST03), with 8 questions worth 75 marks.** Its mark-weighted Difficulty Measure is 0.42 on a 0.20–0.75 scale, with a Difficulty Deviation of 0.17 and a mark split of 25.4% Easy, 53.3% Medium and 21.3% Hard. Algebraic complexity averages 0.40; text density and modelling average 0.48. All five measures use 19 part-level tags, not candidate results. Every question row below repeats them and opens the Interactive Practice Hub for that question.

## Difficulty & complexity profile

All five measures are mark-weighted and calculated from 19 parts carrying 75 part marks. Difficulty tags cover 19 parts, algebraic tags 19 and text-density tags 19. Tags are internal metadata, not official exam-board ratings.

- **Difficulty Measure**: 0.42 — 0.20–0.75 · nearer Medium
- **Difficulty Deviation**: 0.17 — 0 = uniform; higher = more mixed
- **Difficulty Ratio**: 25.4 / 53.3 / 21.3 — % Easy / Medium / Hard
- **Algebraic Complexity Measure**: 0.40 — 0.20–0.75 · nearer Medium
- **Text Density and Modelling Measure**: 0.48 — 0.20–0.75 · nearer Medium

Scale: Easy 0.20 · Medium 0.45 · Hard 0.75, and Low 0.20 · Medium 0.45 · High 0.75 for the two complexity measures. [How each band is defined and how the values are calculated →](https://www.examsci.com/guides/difficulty-and-complexity-measures/)

### Definitions and calculation

| Measure | Paper value | Formula |
| --- | --- | --- |
| **Difficulty Measure** | 0.42 | Σ(d_i × w_i) / Σw_i, with d = 0.20 / 0.45 / 0.75 |
| **Difficulty Deviation** | 0.17 | √(Σw_i(d_i − μ)^2 / Σw_i) |
| **Difficulty Ratio** | 25.4% Easy / 53.3% Medium / 21.3% Hard | marks in band / all tagged marks |
| **Algebraic Complexity Measure** | 0.40 | Σ(c_i × marks_i) / Σmarks_i, with c = 0.20 / 0.45 / 0.75 |
| **Text Density and Modelling Measure** | 0.48 | Σ(t_i × marks_i) / Σmarks_i, with t = 0.20 / 0.45 / 0.75 |

w_i equals the part marks, except for a Hard part worth 4 or more marks, where w_i = marks^0.75 to offset the accessible starter steps inside long structured questions.

## Question list

Each measure is recalculated from the parts of that question and uses the same weights as the paper profile.

| Question | Topic | Marks | Difficulty Measure | Algebraic Complexity Measure | Text Density and Modelling Measure | Practice |
| --- | --- | --- | --- | --- | --- | --- |
| **Q1** FRQ | [2. Sampling](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/sampling/) | 4 | 0.20 Easy | 0.20 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=d34eca6a-789d-4884-9af6-699cc012cf3e&source_detail=WST03%2F01+June+2019) |
| **Q2** FRQ | [4. Goodness of fit and contingency tables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/goodness-of-fit-and-contingency-tables/) | 10 | 0.42 Medium | 0.42 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=3f5b5bb5-5336-4588-acc1-fd121b951acc&source_detail=WST03%2F01+June+2019) |
| **Q3** FRQ | [5. Regression and correlation](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/regression-and-correlation/) | 11 | 0.31 Easy | 0.31 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=44647a31-9fc5-47da-98b4-0330863f9349&source_detail=WST03%2F01+June+2019) |
| **Q4** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 6 | 0.20 Easy | 0.20 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=47bd83d4-6c10-491d-9fca-b7ac7e5931f8&source_detail=WST03%2F01+June+2019) |
| **Q5** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 8 | 0.75 Hard | 0.45 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=c91b9b48-a02e-4852-8e96-4e28966ce7bd&source_detail=WST03%2F01+June+2019) |
| **Q6** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 14 | 0.41 Medium | 0.33 Medium | 0.60 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=302e15f3-5a7e-4722-a5af-379243363a87&source_detail=WST03%2F01+June+2019) |
| **Q7** FRQ | [4. Goodness of fit and contingency tables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/goodness-of-fit-and-contingency-tables/) | 9 | 0.45 Medium | 0.45 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=c6a5f8a0-3bda-4be3-bcba-898c0cc15313&source_detail=WST03%2F01+June+2019) |
| **Q8** FRQ | [1. Combinations of random variables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/combinations-of-random-variables/) | 13 | 0.60 Medium | 0.63 High | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=7627ec36-90f7-46d3-9d56-99726b95349e&question_id=36d49a97-cb62-4bf3-b0d3-894ab30f613f&source_detail=WST03%2F01+June+2019) |

## Topics in this paper

- [2. Sampling](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/sampling/)
- [4. Goodness of fit and contingency tables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/goodness-of-fit-and-contingency-tables/)
- [5. Regression and correlation](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/regression-and-correlation/)
- [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/)
- [1. Combinations of random variables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/combinations-of-random-variables/)

## Related papers

- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2020-october-wst03-01/) — October 2020 — 7 questions · 75 marks — Free
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## Paper FAQ

**How are the difficulty and complexity measures calculated?**

Each part is weighted by its official marks. Difficulty uses Easy 0.20, Medium 0.45 and Hard 0.75; algebraic complexity and text density and modelling use Low 0.20, Medium 0.45 and High 0.75. A Hard part worth 4 or more marks is down-weighted to marks^0.75, so the accessible starter steps inside a long structured question do not inflate the difficulty result. This paper's Difficulty Measure is 0.42 from 19 parts.

**What does the Difficulty Deviation show?**

It is the mark-weighted standard deviation of the part difficulty values around the paper mean. A value of 0 would mean every tagged part has the same difficulty; this paper's deviation is 0.17, so its parts are more mixed than a single-level paper.

**Is the Difficulty Ratio based on question counts or marks?**

It is based on official marks, not question counts. This paper's shares are 25.3% Easy, 53.3% Medium and 21.3% Hard; the three shares sum to 100% before rounding.

**Are these official difficulty ratings?**

No. They are derived from the platform's part-level difficulty and static-question-profile tags. They are not exam-board grade boundaries and are not calculated from candidate outcomes. Use them to compare the demand profile of papers, not to predict a grade.

**Why does each question row show its own measures?**

Each row recalculates the same mark-weighted formula from that question's parts. A single-part MCQ therefore shows the tag value directly, while a multi-part structured question blends the tags of its parts using the same Hard-part decay as the paper profile.

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Full page with native tables, bar charts and Practice Hub links: https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2019-june-wst03-01/