Statistics & reasoning

Averages, dispersion, sampling; series, coding, syllogism, blood relation.

Mean = Σx/n. Median: middle after sorting (or average of two middles). Mode: most frequent. In a symmetric distribution mean=median=mode.
Range = max−min. Variance = mean squared deviation; SD = √variance. Coefficient of variation = (SD/mean)×100 — comparable across units.
Sampling: random, stratified, systematic, cluster, convenience. Census vs sample. Sampling error vs non-sampling error.
Series: +/−/× patterns, alternate series, squares/cubes. Alphanumeric: positions in alphabet (A=1, Z=26; reverse A=26).
Coding: +1/−1 shift; reverse; opposite letters (A↔Z). Blood relation: draw three generations; in-laws via spouse.
Syllogism: Venn; ‘some’ is reversible; ‘all A are B’ does not imply ‘all B are A’. Possibility cases.
Direction: N-E-S-W; shortest path by Pythagoras if needed. Ranking: position from left + from right = total + 1.
Clock: 30° per hour, 6° per minute; right angle 11 times in 12 hours. Calendar: 400-year Gregorian leap rule; odd days.

Video Lectures & Q&A Discussions

Tap any video card below to watch the lecture directly on YouTube

Focus: Full conceptual lecture and statutory breakdown.

Focus: Top MCQs & PYQ problem-solving discussion.