Typically, a taught masters (there are also MRes type research masters, which are generally much more centered on a thesis/project), will have 3 modules per semester for 2 semesters, and a project-type element towards the end. The problem in answering the question directly is it will depend on how these 6 modules are assessed; it could be an exam, coursework, viva, combination, or something else.
The University you're apply to should make these details available to you, and if not, request it. I'm not an HR expert, but I'd envisage it will probably be one exam per module (so 6 exams), and a dissertation. This is a ballpark average, as you asked for, but the best way to check is to simply ask the University (or Universities) you're applying to. It's been increasingly important across the sector to publish this information clearly (so students don't sue), so you should find them forthcoming on it.