Three measures of central tendency are tested in JEE: Mean, Median, and Mode. The arithmetic mean $\frac{x-bar = sum(xi}{n}$) is the most algebraically tractable and most commonly tested. For grouped data, use direct method or step deviation method for efficiency. Median splits the ordered dataset into two equal halves: for odd n it's the middle value, for even n it's the average of the two middle values. The grouped data formula Median = l + [$\frac{N/2-cf}{f}$]h requires identifying the median class via cumulative frequency. Mode is the most frequent value; for grouped data, Mode = l + [$\frac{f1-f0}{(2f1-f0-f2)}$]h. The empirical relation Mode ≈ 3Median - 2Mean holds for moderately skewed distributions. JEE rarely tests mode directly but may use the empirical relation. Mean is affected by extreme values (outliers), median is resistant to outliers, and mode may not be unique.