Dispersion of data is measured by -a) Coefficient of correlationb) Rangec) Standard deviationd) Coefficient of variatione) Normal distribution curve: (A) a, (B) c, (C) ac, (D) bcd
Answer is D. Measure of dispersion (Variation)

Absolute: Range, Quartile deviation, Mean deviation, standard deviation.
Relative: Co-efficient of range, co-efficient of quartile deviation, coefficient of mean deviation, co-efficient of variation.