Q.The daily wages (in ₹) of 50 workers in a factory are grouped as follows: 0–10: 5 workers, 10–20: 8 workers, 20–30: 15 workers, 30–40: 16 workers, 40–50: 6 workers. Calculate the median wage.

For a continuous series, the median class is located from the cumulative frequency column, and the exact median is then interpolated within it. …

Step 1 — Cumulative frequencies.

Step 2 — Locate the median class. $N=50$, so $N/2=25$. The first cf equal to or greater than 25 is $28$, so the median class is 20–30 ($l=20$, cumulative frequency of the class before it $=13$, $f=15$, $h=10$). …

Graphic cross-check. Section 5 showed that plotting the 'less than' and 'more than' ogives for the same data and reading off their point of intersection gives the median directly from the graph; since both ogives are built from the exact same cumulative frequencies used above, the value read off the graph m …

Using the cumulative frequency OF the median class (28) instead of the cumulative frequency of the class BEFORE it (13) in the formula's numerator is the most common error — it silen …