Logical Reasoning Notes · MDCAT Prep Lab

Analogies test the *relationship* between a pair of words/items, not the words themselves — first name the relationship explicitly (e.g. 'part-to-whole', 'tool-to-user', 'cause-to-effect') before matching it to the answer options.
Common analogy relationship types: synonym/antonym, part-whole, worker-tool, cause-effect, category-member, degree of intensity.
Classification (odd-one-out) questions require identifying the shared property of the majority first, then spotting which single item breaks that pattern — don't just look for the 'odd-looking' item.
Watch for classification traps based on superficial similarity (e.g. spelling pattern) rather than true category membership (e.g. meaning or function).

Number series: check for a constant difference (arithmetic), constant ratio (geometric), alternating pattern, or a squares/cubes-based pattern before guessing.
Letter series: convert letters to their numeric positions (A=1...Z=26) when a pattern isn't obvious visually — this often reveals a hidden numeric series.
Coding-decoding by letter shift: identify a fixed forward/backward shift applied to each letter of the original word (e.g. each letter shifted +2 in the alphabet).
Coding-decoding by substitution: some questions use symbol-for-letter or number-for-letter substitution codes — build the mapping systematically from the given example before applying it to the target word.
Always verify your derived rule against every given letter/number pair in the example, not just the first one — a rule that fits only part of the pattern will lead to a wrong answer.

Draw a quick family tree diagram as you read blood-relation questions — don't try to hold the relationships in your head, since MDCAT relation chains are often 3+ steps long.
Key relation logic: 'mother's brother' = maternal uncle; 'father's sister's husband' = uncle (by marriage); 'son of my father's son' = my nephew or myself, depending on context — resolve gender/identity carefully.
Direction sense questions are solved by sketching a simple compass grid and plotting each movement step by step, tracking net displacement rather than every turn.
For 'shortest distance' questions after multiple turns, use the Pythagorean theorem on the net horizontal and vertical displacement rather than adding up the path length.

A syllogism's conclusion must follow strictly from the given premises alone — never bring in outside/real-world knowledge, even if a premise seems factually false.
Use Venn diagrams for 'All/Some/No' statements: 'All A are B' draws A entirely inside B; 'Some A are B' draws overlapping circles; 'No A are B' draws separate circles.
A conclusion is valid only if it holds true for every possible diagram consistent with the premises — if even one valid diagram contradicts the conclusion, it does not follow.
Statement–assumption questions require distinguishing an assumption (an unstated premise the argument depends on) from an inference (a conclusion that follows from what's stated) — they are commonly confused.
Statement–conclusion questions ask what *must* be true given the statement, not what is merely plausible or likely.

Arithmetical reasoning MCQs are typically short word problems on ratio, percentage, average, speed-distance-time, or simple profit/loss — set up one equation from the problem before attempting mental shortcuts.
For data sufficiency-style questions, check whether each given statement alone is enough to answer the question, then check both together — don't solve the full problem unless the question demands the actual numeric answer.
Percentage-to-fraction shortcuts (e.g. 25% = 1/4, 12.5% = 1/8) save significant time under exam pressure — memorise the common ones.
For average-based questions, remember: total = average × number of items — most 'average' MCQs reduce to this single relationship.