CBN Aptitude Test cheat sheet

Percentage change = (new − old) ÷ old × 100; a rise then a fall of the same rate never returns to the original value.

Simple interest = P × R × T ÷ 100; compound amount = P(1 + R/100)^T, so CI = A − P.

Profit or loss percent is always calculated on cost price unless the question states otherwise; SP = CP × (100 ± p)/100.

Average speed for equal distances at speeds a and b is 2ab/(a + b), not the arithmetic mean.

Work rate adds: if A finishes in x days and B in y days, together they take xy/(x + y) days.

Ratio scaling: to split N in ratio a:b:c, each share = N × (its part ÷ sum of parts).

nth term of an AP = a + (n − 1)d; sum of n terms = n/2 × [2a + (n − 1)d].

In a right triangle, hypotenuse² = sum of squares of the other two sides; common triples are 3-4-5, 5-12-13, 8-15-17.

A valid syllogism needs the middle term distributed in at least one premise; two negative premises yield no conclusion.

Contrapositive is logically equivalent to the original statement; the converse and inverse are not.

"Some A are B" does not imply "some A are not B" in classical logic, but does imply "some B are A".

For passage questions, the correct answer must be supported by stated text; outside knowledge is a distractor.

Words like 'all', 'never', 'only' make a statement strong; 'some', 'often', 'may' make it weak and usually safer in inference items.

Analogies test the same relationship: check part-to-whole, cause-effect, degree, and function before choosing.

In para-jumbles, locate the opening sentence (no pronoun or connector referring backward) and the closing sentence first.

Antonym items: a prefix such as 'in-', 'un-', 'dis-' or a suffix like '-less' often reverses the base word's meaning.

In series completion, test differences, then ratios, then alternating sub-series (odd positions vs even positions).

Rotation rules: 90° clockwise moves a top arrow to the right; 180° reverses direction; mirror images flip left-right, not up-down.

Counting closed regions, line intersections, or sides per figure is the standard method for figure-series progression.

Syllogism validity depends on form, not on real-world truth of the terms.

In seating puzzles, fix one person, draw the circle, and mark 'left/right' relative to the person facing centre (reversed when facing outward).

Blood-relation chains: draw a tree with gender markers; 'brother of my father' = uncle, 'son of my sister' = nephew.

Number-letter coding: convert letters to positions (A=1 … Z=26) and check the shift between consecutive letters.

Odd-one-out items usually hinge on a single property: all but one are prime, symmetric, or share a letter count.

The Central Bank of Nigeria was established by the CBN Act of 1958 and began operations on 1 July 1959.

Nigeria's currency is the naira, subdivided into 100 kobo; the CBN is headquartered in Abuja.

Nigeria gained independence on 1 October 1960 and became a republic in 1963; it operates a bicameral National Assembly (Senate and House of Representatives).

The African Union is headquartered in Addis Ababa; ECOWAS is headquartered in Abuja.

The UN Security Council has five permanent members: China, France, Russia, the UK, and the US.

Nigerian states are grouped into six geopolitical zones; there are 36 states plus the Federal Capital Territory.

The World Bank and IMF were created at the 1944 Bretton Woods conference; both are headquartered in Washington, DC.

Current-affairs items are time-sensitive: verify the office-holder or figure against a recent source before relying on it.

Inflation erodes purchasing power; real interest rate ≈ nominal rate − inflation rate (Fisher approximation).

Demand typically falls as price rises (law of demand); supply typically rises with price (law of supply).

GDP measures final goods and services produced within a country's borders in a period; GNP counts residents' output at home and abroad.

Monetary policy (money supply, policy rate) is run by the central bank; fiscal policy (taxing and spending) is run by government.

A budget deficit occurs when government spending exceeds revenue in a period; public debt is the accumulated stock of borrowing.

Higher reserve requirements reduce the money multiplier; money multiplier ≈ 1 ÷ reserve ratio.

Exchange-rate depreciation makes exports cheaper abroad and imports dearer at home, all else equal.

Liquidity refers to how quickly an asset converts to cash without loss of value; cash is the most liquid asset.

Subject-verb agreement: singular subjects take singular verbs; 'each', 'everyone', 'neither' are singular.

Use 'fewer' with countable nouns and 'less' with uncountable nouns.

Use 'who' for people as subject, 'whom' as object; 'which' for things; 'whose' shows possession.

Apostrophe rules: 'its' = possessive, 'it's' = it is; plural possession adds the apostrophe after the s (students').

Comma splice: two independent clauses need a conjunction, semicolon, or full stop - not a bare comma.

Dangling modifier: the introductory phrase must describe the subject of the main clause.

Comparative uses '-er/more' for two items; superlative uses '-est/most' for three or more.

Prepositions of time: 'in' for months/years, 'on' for days/dates, 'at' for clock times.