Work out cumulative frequency instantly with clear inputs, formula shown and shareable results.
Cumulative frequency is the running total of the class frequencies, showing how many observations fall at or below each class boundary. Plotting it gives the ogive, from which medians and quartiles can be read off.
Cumulative frequency
Cᵏ = f₁ + f₂ + … + fᵏ
5 + 9 + 14 + 20 = 48 out of 60, which is 80%.
Read across at 50% of the total and drop down to the horizontal axis.