CSIR-CRRI JSA cheat sheet

Series completion: check differences first, then ratios, then alternating or two-interleaved series; squares (1,4,9,16), cubes (1,8,27,64) and primes (2,3,5,7,11) recur often.

Coding-decoding: for letter codes, write A=1 to Z=26; opposite-letter pairs sum to 27 (A-Z, B-Y, C-X), and reversal of a word flips positions from the ends.

Blood relations: draw a family tree with + for male and − for female; vertical lines for parent-child, horizontal for spouse or sibling, then read the question off the diagram.

Direction sense: use a compass sketch; net displacement uses Pythagoras, and a right turn followed by a right turn equals a 180° reversal of facing.

Seating arrangement: fix one person first, then place others relative to that anchor; for circular arrangements facing centre, left means clockwise and right means anticlockwise.

Analogy and classification: identify the relation type (part-whole, cause-effect, worker-workplace, synonym-antonym, number-square/cube) before choosing the pair.

Syllogism: in Venn diagrams, a conclusion is valid only if the conclusion is true in every possible diagram consistent with the premises; 'some A are B' does not imply 'some B are not A'.

Number and letter series with mixed operations: when two operations alternate (e.g., ×2 then −3), test the pattern on at least three consecutive terms before committing.

CSIR-CRRI (Central Road Research Institute) is a constituent laboratory of CSIR, established in 1952 and located on Mathura Road, New Delhi; it works on roads, pavements, bridges and traffic engineering.

The Ministry of Road Transport and Highways (MoRTH) publishes the Indian Roads Congress (IRC) codes and the annual 'Road Accidents in India' report; NHAI manages national highway development.

Constitutional facts: the Fundamental Rights sit in Part III (Articles 12-35), Directive Principles in Part IV, and the Right to Education (Article 21A) was inserted by the 86th Amendment, 2002.

IS codes relevant to civil engineering: IS 456 for plain and reinforced concrete, IS 800 for steel structures, IS 2386 for aggregate testing, IS 2720 for soil testing.

Indian geography: the Tropic of Cancer passes through eight states including Gujarat, Rajasthan, Madhya Pradesh and West Bengal; the Deccan Plateau lies between the Western and Eastern Ghats.

Science basics: Portland cement sets by hydration of tricalcium silicate; bitumen is graded by penetration and viscosity; the pH of ordinary water is 7.

Static GK frequently tested: first Indian to win a Nobel Prize (Rabindranath Tagore, 1913), currency of Japan (yen), headquarters of the UN (New York), and the longest river in India (Ganga).

Current affairs focus: new expressways and highway projects, road-safety campaigns, and CSIR achievements in materials, pavement and traffic research.

Speed, distance, time: distance = speed × time; to convert km/h to m/s multiply by 5/18, and m/s to km/h multiply by 18/5.

Percentage change: successive changes of a% and b% give a net change of a + b + ab/100 percent; profit percentage is (SP − CP)/CP × 100 based on cost price.

Simple and compound interest: SI = P × R × T / 100; CI amount = P(1 + R/100)^T; for two years the CI − SI difference equals P(R/100)².

Averages: average = sum / count; if every value is increased by k, the average increases by k; for consecutive numbers the average is the middle term.

Time and work: if A does a job in x days and B in y days, together they take xy/(x + y) days; work rates add, so use 1/x + 1/y = 1/T.

Ratio and proportion: if a : b = c : d then ad = bc; to divide a sum in the ratio m : n, the parts are total × m/(m + n) and total × n/(m + n).

Mensuration: area of circle = πr², circumference = 2πr; volume of cylinder = πr²h; total surface area of cube = 6a²; volume of sphere = (4/3)πr³.

Permutation and combination: nPr = n!/(n − r)! and nCr = n!/(r!(n − r)!); probability of an event = favourable outcomes / total outcomes.

Subject-verb agreement: a singular subject takes a singular verb; with 'either...or' and 'neither...nor', the verb agrees with the nearer subject.

Articles: use 'a' before consonant sounds and 'an' before vowel sounds (an hour, a university); 'the' is used for unique or previously specified nouns.

Tenses: present perfect (has/have + past participle) is used for past actions with present relevance; past perfect (had + past participle) marks the earlier of two past actions.

Prepositions: 'since' with a point of time and 'for' with a duration; 'between' for two items and 'among' for more than two; 'discuss' and 'reach' take no preposition after them.

Voice: to change active to passive, make the object the subject, use the correct form of 'be' plus past participle, and add 'by' before the agent.

Direct to indirect speech: shift the reporting verb to the past, change present to past tense, and adjust pronouns and time words (now → then, today → that day).

Common error traps: 'one of the' takes a plural noun with a singular verb; 'each', 'every' and 'everyone' are singular; 'furniture', 'information' and 'advice' are uncountable.

Vocabulary: synonyms and antonyms, one-word substitutions (e.g., 'philanthropist' for a lover of mankind), and idioms such as 'to let the cat out of the bag' meaning to reveal a secret.