1. [Maximum mark: 6] In a group of 20 girls, 13 take history and 8 take economics. Three girls take both history and economics, as shown in the following Venn diagram. The values p and q represent numbers of girls. [Diagram: A rectangle labelled U contains two overlapping circles labelled history and economics. The history-only region is labelled p, the intersection is labelled 3, and the region outside both circles is labelled q.] (a) Find the value of (i) p; (ii) q. [4] (b) A girl is selected at random. Find the probability that she takes economics but not history. [2]