IB Maths AI HL May 2025 TZ3: what the examiners reported

Internal assessment showed the same improvement and the same weaknesses as other zones, notably templated projects and thin reflection. On paper 1 the HL-only topics scored poorly and basic algebra and rounding let many down, while paper 2 exposed gaps in complex numbers, vectors in context and linear combinations. Paper 3 was accessible, but some strong candidates scored nothing on parts their school had not taught.

By Pietro Meloni, PhD · Summarised from the IB subject report on

Maths AI HL grade boundaries, May 2025 TZ3: minimum mark for each grade. Every session
ComponentMax4567
Overall10038526577
Internal assessment209121517
Paper 111037506477
Paper 211038536883
Paper 35527344047

HL Paper 1

Common material was handled confidently, but HL-specific topics gave consistently low scores, suggesting some were barely taught, and basic algebra and rounding were weak.

Found difficult

  • summary statistics
  • chain rule
  • product rule
  • markov chains
  • eigenvalues and eigenvectors
  • separable differential equations
  • type i and type ii errors
  • kinematics
  • volumes of revolution
  • linearizing data
  • matrix transformations
  • coordinate geometry
  • sampling methods

Well prepared

  • chi-squared test for independence
  • linear regression
  • sine and cosine rules
  • logarithms and indices
  • financial mathematics
HL Paper 1: question by question, in my words.
QTopicHow it wentWhere marks were lost
1sine and cosine rules and shortest distance to a lineMixedcalculator left in radian mode; measured to a median or angle bisector instead of the perpendicularTip: Check the angle mode after a reset, and remember the shortest distance is perpendicular.
2exponential model solved with logs or the solverAnswered welldid not write the solution in the form requestedTip: Rewrite your answer in exactly the form the question asks for.
3chi-squared test for independenceAnswered wellwrong rule for rejecting or accepting the null hypothesisTip: Reject the null hypothesis only when the p-value is below the significance level.
4reading and drawing box plots with outliersMixeddid not see that each quarter holds 25% of data; misread Q1 by one grid division; did not mark outliers on the drawn box plotTip: Read scales carefully and show outliers as separate points with the whisker ending before them.
5loan repayments and early settlement with the finance solverMixedcould not assign solver values for an early repaymentTip: Sketch a timeline of the loan to decide which values go into each solver field.
6geometric probability with an arithmetic series and a binomial modelMixeddid not recognise a binomial situation; misinterpreted the binomial resultTip: Check for a fixed number of independent trials with constant probability to spot a binomial model.
7sampling methods and linear regressionAnswered wellcould not name the sampling techniqueTip: Learn the names and features of each sampling method in the guide.
8matrix transformations and reversing themMost struggledoften left blank; multiplied matrices in the wrong order or incompatible sizes; could not find the original point from its imageTip: Use the inverse matrix to undo a transformation, and check matrix order before multiplying.
9product and chain rule and the tangent slopeMost struggledforgot to multiply by the inner derivative; skipped part (b) after struggling in (a)Tip: With the chain rule, never forget the factor coming from differentiating the inside function.
10inverse square variation and linearizing with logsMost struggledguessed the wrong proportionality; did not see that F against d to the minus 2 is a line through the originTip: Plotting against the transformed variable turns variation into a line whose gradient is the constant.
11coupled differential equations, eigenvalues and Euler's methodMixedsolved the characteristic equation when not needed; could not run the booklet iteration on the GDC to fill the tableTip: Practise setting up Euler's method for a coupled system on your own GDC before the exam.
12type I error with a Poisson distributionMixeddefined a type I error but could not calculate it; chose the wrong Poisson parameter; did not relate Poisson assumptions to the contextTip: A type I error probability is the chance of landing in the critical region when the null is true.
13separable differential equation for a proportionMost struggleddid not know separation of variables; missed the factor of minus one when integrating; substituted 90 instead of 90 percentTip: Watch the sign from the inner derivative when integrating 1 over (1 minus P).
14vector kinematics by integrationMost struggledleft out the constant of integration; could not interpret the physical contextTip: Use initial conditions to find the constant whenever you integrate velocity or acceleration.
15eigenvectors and steady state of a Markov chainMost struggledcould not find the eigenvector for eigenvalue 1; could not get the steady state with a non-numeric matrixTip: The steady state is the eigenvector for eigenvalue 1 scaled so its entries add to 1.
16translating a curve and the volume of a half revolutionMost struggleddid not bracket x + 0.3; applied the shift to the wrong component; did not subtract two volumes; ignored that only half a revolution was madeTip: Draw the region and decide whether the volume is a difference of two solids before integrating.

What to practise

  • Explain the reasons behind methods, notably for Markov chain eigenvectors, motion problems and solids of revolution.
  • Build fluency in differentiation, separation of variables and integration through varied practice.
  • Focus on interpreting statistics, including error types, assumptions and sampling.
  • Practise geometric reasoning with distances, box plots and forward and reverse matrix mappings.
  • Check angle mode after calculator resets and practise timed exam questions.

HL Paper 2

Routine mensuration, differentiation and GDC work went well and presentation was often good, but complex numbers, vectors in context and show that reasoning caused trouble.

Found difficult

  • complex numbers
  • linear combinations of random variables
  • vector equation of a line
  • vectors
  • adjacency matrices
  • modelling with functions
  • optimization
  • mathematical argument

Well prepared

  • volume and surface area
  • basic differentiation
  • use of technology
  • mathematical notation
  • rounding and accuracy
HL Paper 2: question by question, in my words.
QTopicHow it wentWhere marks were lost
1volume and surface area of a prism and minimising areaAnswered wellused the wrong base dimensions for the volume; missing or wrong units; skipped the minimisation part; could not justify that the second derivative is positiveTip: To confirm a minimum, explain why the second derivative is positive over the whole domain.
2sinusoidal tide model and solving for timesMixedamplitude given as the full range or the maximum; used the wrong tide level or the earliest intersection; rounded t too early before converting to a time; solved analytically instead of with the GDCTip: Amplitude is half the difference between maximum and minimum; read which crossing the context wants.
3trapezoidal rule and a bridge arch modelMixedwrong strip width or brackets in the trapezoidal formula; divided instead of multiplied by 0.3; gave x without the y-value; checked only the centre of the archTip: Use the mark allocation as a hint that a clearance problem needs more than one check.
4adjacency matrix powers and minimum spanning treeMixedignored the instruction to compute M cubed; did not list every possible route; chose wrong shortest edges; left out the two smallest edges joined to A when finishingTip: Follow the instructed method, and finish the deleted-vertex bound by adding back two edges.
5vectors for motion at constant velocity in three dimensionsMost struggledconfused the position of B with vector AB; squared a negative without brackets; used position vectors as direction vectors; set up the wrong position for P2Tip: Use differences of position vectors for directions and bracket negative values before squaring.
6Poisson mean and a linear combination of normal variablesMixeddid not see that the mean equals the given parameter; used binomial ideas wrongly; squared an earlier answer instead of combining variablesTip: When a total of several normal variables is needed, combine their means and variances directly.
7complex numbers as rotations and a geometric seriesMost struggledconfused the branch length with a coordinate; wrong argument; added ten terms by hand instead of using the sum function; used the wrong common ratioTip: Form an expression for the nth term and apply the GDC sigma tool or the geometric series formula.

What to practise

  • Keep more digits in working to avoid premature rounding.
  • Show what was done on the GDC, such as the matrix computed or equation solved.
  • Practise brief, clear written justifications.
  • Practise interpreting position, direction and velocity vectors in context and learn the guide's vector notation.
  • Cover every topic in the guide, including complex numbers and linear combinations of normal variables.

HL Paper 3

The paper was accessible and the extra time helped many reach the end of question 2, but full marks needed broad mastery and some untaught topics gave zeros.

Found difficult

  • voronoi diagrams
  • expected value
  • algebraic manipulation
  • use of technology
  • summary statistics

Well prepared

  • coordinate geometry
  • hypothesis testing
  • linear regression
  • problem solving
HL Paper 3: question by question, in my words.
QTopicHow it wentWhere marks were lost
1Voronoi cells for air quality, triangle area and a test on a meanMixedused long algebra where inspection sufficed; computed distances to every site; started a show that from the result; forgot to divide sigma by root n; treated the normal distribution as discreteTip: Look for the simplest method first, such as half base times height for a triangle.
2logistic growth model, rearranging and rates of changeMixedmissing brackets when rearranging; used t = 19 instead of 20; multiplied by only one factor; could not set up the charging point equationTip: If you cannot do a part, invent a value and use it to earn follow-through marks later.

What to practise

  • Cover the whole syllabus, especially hypothesis testing.
  • Practise show that questions without working backwards from the given result.
  • Encourage students to consider simpler techniques and use command terms and marks as guides.

Internal assessment

What moderators raised about the exploration this session, criterion by criterion.

  • A. aims unclear or abandoned, too much explanation of on-syllabus methods and repetitive work
  • B. calculator notation, unreadable diagrams, large tables in the body and no equation editor
  • C. explorations that leave little scope for independent thinking
  • D. lengthy descriptive reflections and generic AI-style lists of limitations
  • E. procedural mathematics without explaining why techniques suit the task
  • E. chi-squared used to assess curve fit and test conditions not checked
  • E. nearest neighbour tried from a single start and Voronoi diagrams used in unsuitable contexts

About this summary

After every session the IB sends schools a subject report: how candidates did on each paper and question, and what teachers should work on. This page is my reading of the Maths AI HL report for May 2025 TZ3, in my own words. No text from the report or from the exam questions is reproduced, and it is not endorsed by the International Baccalaureate.

Session codes: TZ is the time zone variant of the papers. Other variants of the same session: May 2025 TZ2, May 2025 TZ1. Corrections: pietro@pietromeloni.com.

Frequently asked questions

Which questions were hardest in Maths AI HL May 2025 TZ3?

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The questions most candidates struggled with were on matrix transformations and reversing them, product and chain rule and the tangent slope, inverse square variation and linearizing with logs and separable differential equation for a proportion. The tables above list every question discussed in the report, paper by paper.

What did candidates find difficult in May 2025 TZ3?

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Across the papers the examiners listed summary statistics, chain rule, product rule, markov chains, eigenvalues and eigenvectors, separable differential equations, type i and type ii errors and kinematics, among others.

What were the grade boundaries for Maths AI HL May 2025 TZ3?

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Maths AI HL: a 7 from 77 out of 100 overall in May 2025 TZ3. The component boundaries are in the table on this page.

Is this the official IB subject report?

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No. It is my summary of the report the IB issues to schools after each session, rewritten in my own words with a teacher's reading of it. No text from the report or from exam questions is reproduced. Your school's IB coordinator can access the original.

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