Exam questions consistency checking

This paper deals with the problem of checking consistency of automatically generated exam questions in e-learning systems. We focus on the exam questions with the numeric solutions and the automatic evaluation of their answers. Each answer is evaluated as correct if it is within a specified range from the actual correct value. In our paper we check the consistency of exam questions evaluated with this simple method, i. e. are the answers calculated using wrong methods and based on false assumptions always evaluated as incorrect. We made a mutant testing algorithm for identifying inconsistent questions using model checking. At the end we present use cases based on the evaluation of students' answers on our courses Fundamentals of Electrical Engineering and Formal Methods in System Design.