The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.

Here, we use the step deviation method to find the mean.
Let's take assumed mean, A as 70
Class interval = 10
∴ ui = (xi - A)/h = (xi - 70)/10
mean (x̄) = A + h Σ(fiui) / Σfi = 70 + 10 × -2 / 35 = 70 - 0.57 = 69.43
Hence, the mean literacy rate is 69.43