# 9709/73 October/November 2017

> 9709/73 October/November 2017: 8 questions, 50 marks. Difficulty 0.40, deviation 0.14, algebraic 0.35, text density 0.53. CIE IAL Mathematics 9709 P7.

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CIE IAL · Mathematics · 2017 October/November

This Mathematics 9709 Paper 7 (Probability & Statistics 2) paper contains 8 questions worth 50 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.

- CIE IAL
- 9709 P7
- 8 questions
- 50 marks
- Free paper
- [Practise this paper](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5)
- [All 9709 P7 papers](https://www.examsci.com/past-papers/cie-ial/mathematics/9709-p7/)

Core finding

**9709/73 October/November 2017 is a past paper for CIE IAL Mathematics 9709 Paper 7 (Probability & Statistics 2), with 8 questions worth 50 marks.** Its mark-weighted Difficulty Measure is 0.40 on a 0.20–0.75 scale, with a Difficulty Deviation of 0.14 and a mark split of 26.0% Easy, 64.0% Medium and 10.0% Hard. Algebraic complexity averages 0.35; text density and modelling average 0.53. All five measures use 13 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 13 parts carrying 50 part marks. Difficulty tags cover 13 parts, algebraic tags 13 and text-density tags 13. Tags are internal metadata, not official exam-board ratings.

- **Difficulty Measure**: 0.40 — 0.20–0.75 · nearer Medium
- **Difficulty Deviation**: 0.14 — 0 = uniform; higher = more mixed
- **Difficulty Ratio**: 26.0 / 64.0 / 10.0 — % Easy / Medium / Hard
- **Algebraic Complexity Measure**: 0.35 — 0.20–0.75 · nearer Medium
- **Text Density and Modelling Measure**: 0.53 — 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** | 0.40 | Σ(d_i × w_i) / Σw_i, with d = 0.20 / 0.45 / 0.75 |
| **Difficulty Deviation** | 0.14 | √(Σw_i(d_i − μ)^2 / Σw_i) |
| **Difficulty Ratio** | 26.0% Easy / 64.0% Medium / 10.0% Hard | marks in band / all tagged marks |
| **Algebraic Complexity Measure** | 0.35 | Σ(c_i × marks_i) / Σmarks_i, with c = 0.20 / 0.45 / 0.75 |
| **Text Density and Modelling Measure** | 0.53 | 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 | 1 The Poisson distribution | 3 | 0.20 Easy | 0.20 Low | 0.20 Low | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=3864e2ef-77f5-41a6-a671-e8ae73da2800&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q2** FRQ | 1 The Poisson distribution | 4 | 0.45 Medium | 0.20 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=485da808-1970-45e6-a6a8-e66fa7d2df19&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q3** FRQ | 4 Sampling and estimation | 4 | 0.45 Medium | 0.45 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=20bf504c-2822-426f-baf6-271f46c8c141&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q4** FRQ | 4 Sampling and estimation | 4 | 0.20 Easy | 0.20 Low | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=a309f138-9e9e-4f92-8ff1-c2ab74438fd7&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q5** FRQ | 3 Continuous random variables | 6 | 0.33 Medium | 0.33 Medium | 0.20 Low | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=08da7576-f2be-4df1-9dad-5c79df4ab3a7&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q6** FRQ | 2 Linear combinations of random variables | 8 | 0.36 Medium | 0.36 Medium | 0.45 Medium | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=e5fefbb6-c97e-488a-9a1f-e242418501dd&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q7** FRQ | 5 Hypothesis tests | 9 | 0.45 Medium | 0.37 Medium | 0.75 High | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=fd99c214-4747-4f71-b882-4b35d7e415d1&source_detail=9709%2F73+October%2FNovember+2017) |
| **Q8** FRQ | 4 Sampling and estimation | 12 | 0.55 Medium | 0.45 Medium | 0.75 High | [Go to Practice Hub](https://www.examsci.com/practice?set_id=e56afe1f-c6f1-46d3-945e-1d7fa66c5ae5&question_id=88aab935-d22e-4bd3-8269-2c400d0a1aa6&source_detail=9709%2F73+October%2FNovember+2017) |

## Related papers

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- [9709/73](https://www.examsci.com/past-papers/cie-ial/mathematics/9709-p7/2017-may-june-9709-73/) — May/June 2017 — 7 questions · 50 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 0.40 from 13 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 0.14, 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 26.0% Easy, 64.0% Medium and 10.0% 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/cie-ial/mathematics/9709-p7/2017-october-november-9709-73/