NCERT Example 10 - Statistics

Question: For classes 30-40, 40-50, ..., 90-100 with frequencies 3, 7, 12, 15, 8, 3, 2, find variance and standard deviation.

Answer: Mean = 62, variance = 201, standard deviation approximately 14.18.

Full step-by-step NCERT solution with diagrams on Something by Zero.