Different mathematic course units have different assessment methods, varying from 100% coursework to 100% examamination.  A number of course units have a mixture of coursework and end of semester examination.  The information on how each course unit is assessed is available by accessing the course desrciptions for a course unit from the following wepage:

http://www.maths.manchester.ac.uk/study/undergraduate/information-for-current-students/course-units-offered/

Detailed information on assessment and examinations can be found in the Schools Examination document: Examinations Document v23 (all taught students)