TNUSRB Constable key terms

A set of quantities added together and then divided by how many quantities there are. In numerical ability tests you often must find the average, or work backwards from a given average to find a missing value.

A comparison of two quantities of the same kind, written as a:b, showing how many times one contains the other. Ratios are used to share amounts, compare speeds, and solve mixture and partnership problems.

A statement that two ratios are equal, such as a:b = c:d. In a true proportion the product of the outer terms equals the product of the inner terms, which lets you find an unknown quantity.

A fraction expressed as a part of one hundred, so 25% means 25 out of every 100. Percentage problems cover increase, decrease, profit and loss, discount, and simple interest calculations.

Interest calculated only on the original principal for the whole period, using the formula P × R × T ÷ 100. It does not earn interest on interest, unlike compound interest.

Interest added to the principal at fixed intervals so that later interest is calculated on a growing amount. The amount is found using P(1 + R/100)^n, and it always exceeds simple interest for the same rate and time.

The highest common factor: the largest number that divides each of the given numbers exactly. It is used to split quantities into the biggest equal groups and to simplify fractions.

The least common multiple: the smallest number that is a multiple of each of the given numbers. It is used for problems about bells ringing together, runners meeting again, and adding fractions with different denominators.

A whole number greater than 1 whose only divisors are 1 and itself, such as 2, 3, 5, 7 and 11. The number 1 is not prime, and 2 is the only even prime.

A number written as one whole number over another, showing parts of a whole, such as 3/4. Operations on fractions require a common denominator for addition and subtraction.

A way of writing fractions using place value to the right of a point, where each place is one tenth of the place before it. Converting between decimals and fractions is a common numerical ability task.

A number that, when multiplied by itself, gives the original number, so 9 is the square root of 81. Square roots of perfect squares up to at least 30 squared are worth memorising for speed.

A sequence of numbers or letters arranged by a rule, such as adding 3 each time or squaring successive numbers. You must identify the rule to find the missing or next term.

A series made only of numbers where the pattern may involve addition, subtraction, multiplication, alternating operations, or differences between differences. Checking the gap between consecutive terms is the fastest first step.

A series built from letters of the alphabet where the gaps follow a pattern in positions, such as skipping one letter or reversing direction. Writing down alphabetical position numbers helps reveal the rule.

A question giving a pair of related items and asking you to complete a second pair with the same relationship, such as worker to tool or cause to effect. Identify the exact relation in the first pair before choosing.

A question listing several items where all but one share a common feature, and you must find the odd one out. The shared feature may be a category, a number property, or a spelling pattern.

A question where words or letters are converted into a code by a fixed rule, and you must decode a new word or encode one. Common rules shift letters by a fixed number of places or reverse the word.

A reasoning question describing family relationships in words or symbols, asking how two people are related. Drawing a simple family tree with clear male and female markers prevents confusion.

A question about a person walking or turning in different directions, asking for the final position or facing direction. Sketching the path with north at the top and marking each turn is the safest method.

A puzzle placing people in a line or around a circle from clues about who sits beside or opposite whom. Circular arrangements face either the centre or outward, which reverses left and right.

Overlapping circles used to show how sets of items relate, including shared and unshared members. Questions ask for counts in a region, or which diagram best represents a given group of categories.

A reasoning topic about the angle between hour and hand positions, or about clocks gaining and losing time. The minute hand moves 6 degrees per minute and the hour hand 0.5 degrees per minute.

A reasoning topic about day of the week for a given date, odd days in a year, and leap years. A normal year has one odd day and a leap year two, which determines the shift in weekday.

A longitudinal mechanical wave that travels through a medium as compressions and rarefactions. It cannot travel through a vacuum, and its speed is greatest in solids and least in gases.

An electromagnetic wave that travels without a medium at about 3 × 10^8 metres per second in vacuum. It shows reflection, refraction, and dispersion, and its colour depends on wavelength.

The number of complete oscillations or cycles a wave makes in one second, measured in hertz. Higher frequency means higher pitch for sound and shorter wavelength for light.

Three laws describing motion: a body stays at rest or in uniform motion unless a force acts; force equals mass times acceleration; and every action has an equal and opposite reaction. They explain inertia, momentum, and rocket propulsion.

The attractive force between any two masses, proportional to the product of the masses and inversely proportional to the square of the distance between them. On Earth it gives objects an acceleration of about 9.8 metres per second squared.

The force that opposes relative motion between two surfaces in contact, converting kinetic energy into heat. It can be reduced with lubricants or ball bearings, and it is essential for walking and braking.

The process by which green plants use sunlight, carbon dioxide, and water to make glucose and release oxygen, with chlorophyll as the pigment and chloroplasts as the site. It is the base of most food chains.

The breakdown of glucose inside cells to release energy, using oxygen in aerobic respiration and producing lactic acid or ethanol without it. It is the opposite of photosynthesis in terms of gas exchange.

A protein made by living cells that speeds up a specific chemical reaction without being consumed, such as amylase breaking down starch. Enzymes are sensitive to temperature and pH, and are destroyed by high heat.

The pressure exerted by blood against artery walls, recorded as systolic over diastolic pressure in millimetres of mercury. A typical healthy reading is about 120/80, while persistently high values indicate hypertension.

The continuous movement of water between oceans, atmosphere, and land through evaporation, condensation, precipitation, and runoff. It purifies water naturally and drives weather patterns.

A seasonal reversal of wind direction that brings heavy rain, shaping the climate of the Indian subcontinent. The southwest monsoon from June to September supplies most of India's annual rainfall, and Tamil Nadu also depends on the northeast monsoon.

A forest type where trees keep their leaves all year and receive heavy rainfall, typical of the Western Ghats and the Andaman region. It supports dense, layered vegetation and very high biodiversity.

The supreme law of a country setting out the structure of government, the powers of its organs, and the rights of citizens. India's Constitution came into force on 26 January 1950 and is the world's longest written constitution.

Rights guaranteed to citizens in Part III of the Indian Constitution, covering equality, freedom, protection from exploitation, religion, culture and education, and constitutional remedies. They can be enforced through the courts by writ petition.

The study of the structure and working of government, including the legislature, executive, judiciary, and their relationships. In this exam it covers Parliament, the President, panchayats, and the State Legislature.