Question 10
In both diagrams below, neighbouring regions mean that they share a common segment. If two regions just share a common point without a common segment, then these two regions are not neighbouring regions. For example, in diagram B, the regions 1 and 5 are not neighbouring regions. In both diagrams below, Alex wants to paint the regions that have the same number using same colour such that no neighbouring regions are painted in the same colour. What is the minimum number of colours that Alex needs?
