After the graduation ceremonies at a university, seven graduates were asked whether they were in favor of (identified by 1) or against (identified by 0) abortion. Some information about these graduates is shown below. [20 Marks] Graduate Sex Age Abortion Issue Class Rank Nancy F 22 1 3 Michael M 21 1 2 Tammy F 0 1 John M 38 0 Peter M 22 0 12 Marlene F 25 1 4 David M 19 0 8 a. How many observations are in the data set? b. Name the scale of measurement for each variable. c. Which of the variables are categorical and which are quantitative variables? d. Are arithmetic operations appropriate for the variable "abortion issue"? Why?