N is a qualitative, discrete random variable. N is a quantitative random variable. N is a continuous random variable. Let G be the gender of an OU student. G is a discrete random variable since it can take only two values.
G is a continuous random variable.
G is neither discrete nor continuous. Let X be the alkalinity of a detergent solution measured on the pH scale. X is a quantitative, continuous random variable. X is a quantitative, discrete random variable. X is a qualitative random variable, since the quality of a detergent depends on its alkalinity.