What the examiners said about IAL P3 (WMA13) — and exactly what to do about it
We read every Pearson Edexcel examiner report for WMA13 from June 2024 to June 2025, mapped each question to a topic, and turned the comments into a checklist of the mistakes that cost the most marks.
Summaries are in our own words with links to the originals. Predictions are informed guesses, not a guarantee.
Ranked for January 2027
What to focus on for January 2027
IAL units are sat in January, June and October. The October 2026 series is next; the ranking below is for your next sitting, whichever it is. Ranked by how often each area appeared, how many marks it carried and how weakly it was answered.
Informed prediction, not a guarantee: any topic on the specification can be examined.
1
Functions: inverse, composite, range and modulus
The most-examined area (15–22 marks each series), with the inverse domain omission mentioned repeatedly.
Ordered by how often and how widely they were reported. The first 5 are free in full; Pro unlocks the fix and a worked example for every other one.
#1Functions: the domain of an inverse (again), fg versus gf, range
What examiners saw: P3 reports note, series after series, that the domain of the inverse is left out. fg(1) and gf(1) are swapped, and ranges miss an upper or lower bound.
Fix: Domain of f⁻¹ = range of f. For fg, apply g first. Sketch to find the range.
Worked example (our own): f(x) = eˣ + 2, x ∈ ℝ. Find f⁻¹(x) and state its domain.
Loses marks
f⁻¹(x) = ln(x − 2)
Earns the marks
y = eˣ + 2 ⇒ x = ln(y − 2), so f⁻¹(x) = ln(x − 2)
Range of f is f(x) > 2, so the domain of f⁻¹ is x > 2
Why: The domain of the inverse is the range of f. P3 reports mention this omission series after series.
#2Modulus equations and inequalities: extra solutions
What examiners saw: Both cases are solved but invalid solutions are kept, the number of solutions is not checked with a sketch, and inequalities are combined incorrectly.
Fix: Sketch both graphs, then solve each case and check every answer in the original equation.
Worked example (our own): Solve |x − 4| = 2x + 1.
Loses marks
x − 4 = 2x + 1 ⇒ x = −5; −(x − 4) = 2x + 1 ⇒ x = 1. Answer: x = −5, 1
Earns the marks
Case 1: x − 4 = 2x + 1 ⇒ x = −5, but then 2x + 1 = −9 < 0, impossible for a modulus: reject
#3Calculator in the wrong mode (and used instead of calculus)
What examiners saw: In January 2025 some lost three accuracy marks in the first question by working in degrees; elsewhere coordinates of turning points appeared with no (or a wrong) derivative, read from a calculator.
Fix: P3 calculus and root-finding are in radians. Show the derivative and the equation you solved.
Worked example (our own): Show that f(x) = x − cos x has a root between 0.7 and 0.8.
What examiners saw: Candidates try to integrate sin² 3x directly instead of using the double-angle formula, and make sign errors in the formula when they do.
Fix: Rewrite sin²A = ½(1 − cos 2A), cos²A = ½(1 + cos 2A) before integrating.
Worked example (our own): Find ∫ sin²x dx.
Loses marks
= sin³x / 3 + c
Earns the marks
sin²x = ½(1 − cos 2x)
∫ ½(1 − cos 2x) dx = x/2 − (sin 2x)/4 + c
Why: You cannot integrate a power of sin by "adding one to the power". Use the double-angle identity first.
#6Quotient rule: denominator not squared; algebraic division stopped early
What examiners saw: The quotient rule is known but the denominator is not squared or brackets are expanded wrongly; divisions stop before the remainder is correct.
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
What examiners saw: The second solution in the interval is missing, or solutions are not adjusted when the equation is in terms of a compound angle or x = g(y).
Pro: the fix and a worked example (wrong vs right method) for this mistake are in Pro. See plans
How often each topic appeared, and for how many marks
Every question in the papers we read, matched to a topic. Numbers are marks (from the published mark schemes; a question that tests two topics has its marks split). Columns marked * count questions (q) because the marks could not be verified from the mark scheme. Hover or tap a cell to see the questions.
Confidence: high for the series shown — every question was read and mapped by hand. "Series" = how many of the 4 series examined the topic.
Paper by paper
Every paper we analysed, question by question
Topics are ours (matched from each report's question-by-question comments). We don't reproduce the questions: open the official paper from our past-paper page.
A one-page PDF of the ten most common mark-losing mistakes and how to avoid them. Print it and stick it inside your revision folder.
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Sources
Where this comes from
We read the examiner report for every series from June 2024 to June 2025 in full and matched each question to a topic; marks come from the published mark schemes where the per-question totals could be checked against the paper total.
What do examiners say students get wrong in IAL P3 (WMA13)?
The most repeated points are: Functions; Modulus equations and inequalities; Calculator in the wrong mode (and used instead of calculus). Each one on this page has the fix and, where free, a worked example showing the wrong and right method.
Which IAL P3 (WMA13) topics come up most?
In the material we analysed, the biggest areas were Functions and the modulus function, Chain, product and quotient rules, Exponential models and log graphs.
Is this a prediction of the January 2027 paper?
No one outside the exam board knows what will be on the next paper. The "focus" list is an informed prediction from how often topics appeared and how weakly they were answered; it is not a guarantee, so revise the whole specification.
Where does this information come from?
We read 4 Pearson Edexcel examiner reports (June 2024, October 2024, January 2025, June 2025) in full, summarised them in our own words and linked each point to the original.
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