Ogives (cumulative frequency curves)
Descriptive statistics · Mathematics
Study notes
Q: Classes 0-10 (cf 5), 10-20 (cf 13), 20-30 (cf 25), 30-40 (cf 31). Estimate the median from the ogive. n = 31, n/2 = 15.5. Plot points (10,5), (20,13), (30,25), (40,31), join smoothly. Find y = 15.5 on the curve: between (20,13) and (30,25). Interpolate: x approx 20 + (15.5-13)/(25-13) times 10 = 20 + 2.08 = 22.08. Median approx 22.1.