Tell whether each of the following involves a categorical variable, a discrete quantitative variable, or a continuous quantitative variable.
a. Number of McDonald's restaurants in various countries around the world
b. Time before a child's epileptic seizure that the family dog shows signs of anticipation
c. Whether or not a pedometer reports mileage accurately
d. Students' self-rating of intelligence, on a scale of 1 to 7
e. Femur bone lengths of dinosaur specimens
f. What language is spoken in various American households
g. The proportion of households with Spanish as the first language in each of the 50 states