You always have to have contingency fuel. You cannot fly legally without it.
The JAA expects you to know that you must include it, so they leave it out of the question setting to test you to see whether you remember to include it. Always add it if it is not already given.
Except for those silly questions about 30% of the trip fuel for light aircraft operations, the JAA assume that the contingency fuel is always 5% of the trip fuel. In fact, there are various options in real life, including 3%, 20 minutes, 5 minutes, or a figure based on a statistical reduction method. However, in the fantasy world of JAA ATPL exams, always use 5%.