Bac Série H Côte d'Ivoire common mistakes
Bac Série H Côte d'Ivoire · Understand the traps and how to avoid them.
In a bac H applied-maths problem on cost/revenue/profit, the candidate writes the derivative of a quotient or a product by differentiating numerator and denominator (or each factor) separately, e.g. treats (3x+5)/(x+2) as giving 3/1 = 3, then builds the whole study of the function and the break-even point on that false derivative.
The quotient and product rules are learned late in the year and are often mixed up under exam pressure; students pattern-match to the simpler polynomial rule (u+v)' = u'+v' because it is the one they have practised most, and they rarely re-check the derivative against a rough graph or a numeric test.
What to do instead
Before any sign table or variation table, write the rule explicitly at the top of the working: (uv)' = u'v+uv', (u/v)' = (u'v-uv')/v². Then verify the result numerically on one point (compare the computed derivative with a finite-difference slope (f(a+0,01)-f(a))/0,01), and only then start the sign study. Keep a one-page formula card and drill ten mixed derivatives per session until the choice of rule is automatic.
On a probability question (drawing balls, defective items, customer arrivals), the candidate computes a conditional probability as P(A∩B) = P(A)×P(B) without checking independence, or answers a 'given that' question with P(B) instead of P(B|A); in a two-stage tree they add the branch probabilities along a path instead of multiplying them.
The formula P(A∩B) = P(A)P(B) is the first one memorised and it is applied everywhere because the independence condition is treated as a formality; the wording 'sachant que' is not read as a signal, and the tree rules (multiply along a path, add across branches) are confused because both operations appear in the same exercise.
What to do instead
Adopt a fixed reading routine: underline 'sachant que' / 'parmi ceux qui' and immediately write P(B|A) = P(A∩B)/P(A). On every tree, label each branch with a conditional probability, write '×' on the path and '+' at the junction, and state the independence check (compare P(A∩B) with P(A)P(B)) before ever using the product formula. Do three corrected exercises per week where the answer must be justified by one of the two formulas named explicitly.
In statistics, the candidate computes the mean of a grouped series by averaging the class centres without weighting by the frequencies (or uses the class bounds instead of the centres), and reports a standard deviation or a median taken from the wrong column of the table.
Grouped data are often presented in a table where the centre column is already filled in, so students read across instead of weighting down; the median class is confused with the modal class, and calculators with statistical mode are used without checking which list is x and which is the frequency.
What to do instead
Rewrite the table by hand with three added columns: centre x_i, product n_i·x_i, and n_i·x_i². Compute the mean as Σn_i x_i / Σn_i, show the cumulative frequencies to locate the median class, and identify the modal class as the one with the largest n_i (not the largest centre). Cross-check the mean lies between the smallest and largest class centres before writing the conclusion.
In general accounting, the candidate records a purchase of goods on credit by debiting the supplier account and crediting the purchases account, or omits the TVA (VAT) entry, so the balance sheet and the result no longer balance; the trial balance is then 'forced' by adding a plug figure.
The debit/credit direction is learned by memorising lists rather than by the meaning of the accounts (a supplier is a debt, therefore a credit), and VAT is treated as an accessory rather than as a separate account (État, TVA récupérable / TVA facturée). The plug figure hides the error instead of revealing it.
What to do instead
For every entry, first say aloud what happens economically ('I owe money to the supplier; I receive goods; I recover VAT'), then choose the accounts. Write the entry in the journal with the three lines (601 or 60 purchase, 4452 TVA récupérable, 401 supplier) and immediately post it to the ledger. At the end, prove the balance by Σdebits = Σcredits on the trial balance and investigate any gap rather than plugging it; keep a personal list of the ten accounts used most in the exam.
In cost accounting (comptabilité analytique), the candidate allocates all indirect costs to products using a single rate (e.g. per unit produced or per direct labour hour) even when the exercise gives separate cost centres, and then concludes on profitability from that distorted unit cost; or forgets to value ending inventory when computing the cost of goods sold.
Single-rate allocation is the only method many candidates have practised, and the section on cost centres (centres d'analyse, unités d'œuvre) is skipped as 'too long'. The link between production cost, cost of goods sold and inventory change is not understood, so the result is computed on production rather than on sales.
What to do instead
Before calculating, draw the flow: direct costs → cost centres → units of work (unités d'œuvre) → products → cost of goods sold. Allocate each indirect cost only to the centre that consumes it, using the driver given in the statement, and always compute cost of goods sold = production cost + opening inventory − closing inventory. Finish with a short comment stating which product is profitable and why the allocation choice matters.
In economics, the candidate answers a question on elasticity, inflation or GDP by reciting a definition instead of performing the calculation asked, or confuses a variation of price with a variation of quantity when computing price elasticity, giving a sign and a magnitude that contradict the demand curve.
Definitions are easier to memorise than mechanisms, and the exam wording ('calculez', 'interprétez') is not distinguished from 'définissez'. The elasticity formula is remembered without its sign convention and without the distinction between elastic and inelastic demand.
What to do instead
Train on the instruction verbs: 'définir' = one sentence plus an example; 'calculer' = formula, substitution, result with unit; 'interpréter' = one sentence linking the number to behaviour ('a 1 % price rise reduces quantity demanded by 2 %, so demand is elastic'). Always write the elasticity formula with the absolute value and state the interpretation before commenting on the economic consequence.
In business organisation and management questions, the candidate describes a company's structure or a motivation theory in general terms without naming the authors, the type of structure, or applying it to the case given, so the answer could apply to any company.
Management chapters are perceived as 'common sense' and are revised by reading rather than by producing structured answers; students do not build a repertoire of named models (Taylor, Fayol, Maslow, Herzberg, Mintzberg) and therefore cannot anchor their argument.
What to do instead
Build a one-page model sheet per chapter: author, date, key idea, one criticism, one example. In the exam, answer with the structure 'model named → definition in two lines → application to the case in the statement → limit'. Practise on past case studies with a strict time limit so that the application paragraph, not the definition, carries most of the marks.
In the marketing or HRM question, the candidate lists all four Ps or all the stages of a recruitment process without selecting the ones relevant to the case, and gives no figures (price positioning, margin, cost per hire) even when the statement supplies data.
Lists are easy to reproduce and give an illusion of completeness; students fear omitting a point more than they value relevance. Quantitative data in the statement are read as decoration rather than as material to be used.
What to do instead
Rewrite the question as a decision ('which price?', 'which recruitment channel?') and answer with two or three options compared on explicit criteria, using the figures given. End with a justified recommendation in one sentence. Deliberately leave out irrelevant Ps and say why they are not decisive here - the marker rewards selection.
In the IT/office-software part, the candidate writes a spreadsheet formula by copying a pattern without anchoring references (e.g. =B2*C2 dragged down while the rate sits in a fixed cell), or writes a database query/relational schema that stores repeated data in one table, producing redundancy and update anomalies.
The dollar sign in absolute references is memorised as syntax rather than as a meaning, and normalisation is studied as theory without being applied to a concrete table; students also confuse a field, a record and a table when describing a file.
What to do instead
For spreadsheets, always ask 'should this reference move when I copy?' and use $ on the part that must stay fixed; test by copying to one cell and checking the result. For databases, apply the checklist: one theme per table, no repeating group, every non-key field depends on the whole key; then draw the tables with primary and foreign keys and show one example record. Rehearse on a small library or sales case.
In the law/labour-law and business-law questions, the candidate answers with moral judgement ('it is unfair', 'the employer must be nice') instead of the rule, its source and its consequence; the type of contract (CDD vs CDI) or the competent court is asserted without reference to the applicable condition.
Legal reasoning is new in the curriculum and candidates transpose everyday opinion into the answer; the hierarchy of sources (Constitution, law, decree, collective agreement) and the conditions of validity of a contract are known as slogans but not as a test to be applied step by step.
What to do instead
Use a fixed three-step frame for every legal question: qualify the facts (what type of contract, what breach), state the rule with its source (article or code, collective agreement), then apply it to conclude. For a CDD, check the legal cases of recourse and the written form; for a dismissal, check the real and serious cause and the procedure. Keep a table of the courts and their competence and revise it weekly.