# WST03/01 June 2015

> WST03/01 June 2015: 8 questions, 75 marks. Difficulty 0.42, deviation 0.15, algebraic 0.38, text density 0.47. Edexcel IAL Mathematics S3.

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Edexcel IAL · Mathematics · 2015 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=696adb49-011e-4547-9482-ae0661c007cc)
- [All S3 papers](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/)

Core finding

**WST03/01 June 2015 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 0.15 and a mark split of 22.7% Easy, 61.3% Medium and 16.0% Hard. Algebraic complexity averages 0.38; text density and modelling average 0.47. All five measures use 21 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 21 parts carrying 75 part marks. Difficulty tags cover 21 parts, algebraic tags 21 and text-density tags 21. Tags are internal metadata, not official exam-board ratings.

- **Difficulty Measure**: 0.42 — 0.20–0.75 · nearer Medium
- **Difficulty Deviation**: 0.15 — 0 = uniform; higher = more mixed
- **Difficulty Ratio**: 22.7 / 61.3 / 16.0 — % Easy / Medium / Hard
- **Algebraic Complexity Measure**: 0.38 — 0.20–0.75 · nearer Medium
- **Text Density and Modelling Measure**: 0.47 — 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** | 0.15 | √(Σw_i(d_i − μ)^2 / Σw_i) |
| **Difficulty Ratio** | 22.7% Easy / 61.3% Medium / 16.0% Hard | marks in band / all tagged marks |
| **Algebraic Complexity Measure** | 0.38 | Σ(c_i × marks_i) / Σmarks_i, with c = 0.20 / 0.45 / 0.75 |
| **Text Density and Modelling Measure** | 0.47 | 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/) | 5 | 0.20 Easy | 0.20 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=fdd6be5d-1f09-490e-8dc4-db29c4c80bcb&source_detail=WST03%2F01+June+2015) |
| **Q2** FRQ | [5. Regression and correlation](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/regression-and-correlation/) | 9 | 0.45 Medium | 0.34 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=58202ee3-87a1-4a54-b9cd-8e0f6c9a71b2&source_detail=WST03%2F01+June+2015) |
| **Q3** 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/) | 11 | 0.43 Medium | 0.43 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=7b31f1f8-b22a-4186-a3f2-8db98a2e865f&source_detail=WST03%2F01+June+2015) |
| **Q4** FRQ | [1. Combinations of random variables](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/combinations-of-random-variables/) | 11 | 0.45 Medium | 0.45 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=f41c7011-3782-428a-a013-e05b144c720b&source_detail=WST03%2F01+June+2015) |
| **Q5** 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/) | 12 | 0.75 Hard | 0.45 Medium | 0.75 High | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=b9da7c3e-775f-47b6-949d-52c68f418f94&source_detail=WST03%2F01+June+2015) |
| **Q6** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 13 | 0.33 Medium | 0.33 Medium | 0.41 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=891bf10d-e1e5-4647-9ee1-5085c591c1e2&source_detail=WST03%2F01+June+2015) |
| **Q7** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 5 | 0.35 Medium | 0.35 Medium | 0.35 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=b4c8a78a-0f54-4f86-ac6d-662bdc5751e0&source_detail=WST03%2F01+June+2015) |
| **Q8** FRQ | [3. Estimation, confidence intervals and tests](https://www.examsci.com/topics/edexcel-ial/mathematics/statistics-3-wst03/estimation-confidence-intervals-and-tests/) | 9 | 0.37 Medium | 0.37 Medium | 0.37 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=696adb49-011e-4547-9482-ae0661c007cc&question_id=aa27dbdc-4097-4609-85ae-cffc70af7ead&source_detail=WST03%2F01+June+2015) |

## Topics in this paper

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

## Related papers

- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2016-june-wst03-01/) — June 2016 — 8 questions · 75 marks — Free
- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2014-june-wst03-01/) — June 2014 — 7 questions · 75 marks — Free
- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2017-june-wst03-01/) — June 2017 — 8 questions · 75 marks — Free
- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2018-june-wst03-01/) — June 2018 — 7 questions · 75 marks — Free
- [WST03/01](https://www.examsci.com/past-papers/edexcel-ial/mathematics/statistics-3-wst03/2019-june-wst03-01/) — June 2019 — 8 questions · 75 marks — Free
- [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

## 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 21 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 0.15, 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 22.7% Easy, 61.3% Medium and 16.0% 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-wst03/2015-june-wst03-01/