Median = l + [$\frac{N/2 - cf}{f}$]*h. To find: (1) compute N/2, (2) find the class whose cumulative frequency first exceeds N/2 (median class), (3) l = lower boundary of median class, cf = cumulative frequency of the class just before median class, f = frequency of median class, h = class width. For ungrouped data with even n: median = average of $\frac{n}{2}$th and (n/2+1)th values.