1. A question setting apparatus, comprising: a storage part; a processor; and a program that is stored in the storage part and, when executed by the processor, causes the processor to perform a process, wherein the storage part stores a problem database which maintains problem data including a problem, a correct answer to the problem, and a problem identifier to identify the problem; a reference answer percentage, a reference correct answer percentage, a reference answer time, and a reference percentage of students exceeding the reference answer time; and a student answer database which maintains answer data including answers of respective students for the problem, the problem identifier which corresponds the answers to the problem, answer times taken by respective students to answer the problem, and a correct/incorrect answer determination results for the respective students, the processor is configured to transmit, through a network, the problem and the problem identifier to respective student terminals of the respective students connected to the question setting apparatus through the network, to thereby administer a test in which the problem is displayed by the student terminal, and when the processor executes the program, the process performs in response to receiving respective answer data during the test from the respective student terminals of the respective students, for each of the respective answer data: recording the respective answer data, which includes an answer time taken to answer the problem, producing the correct/incorrect answer determination result by using the problem database and the problem identifier included in the respective answer data to identify the problem and the correct answer of the problem, and recording the correct/incorrect answer determination result; during the test, to determine a comprehension level of the students in comprehending the problem, using answer data recorded in the student answer database to determine a first percentage of a number of students who answered the problem with respect to a total student number, in response to the first percentage being determined to exceed the reference answer percentage, determining that the comprehension level is a trigger to notify a user of the question setting apparatus to generate a supplemental explanation of the problem, upon determining that a second percentage of a number of correct answers with respect to the number of students who answered the problem is lower than the reference correct answer percentage, the second percentage determined based on the correct/incorrect answer determination results recorded in the student answer database, and in response to the first percentage being determined as not exceeding the reference answer percentage, determining that the comprehension level is a trigger to notify the user of the question setting apparatus to generate a supplemental explanation of the problem, upon determining that a third percentage of the students who exceed the reference answer time is higher than the reference percentage of students exceeding the reference answer time, the third percentage determined based on the answer times recorded in the student answer database; in response to determining that the comprehension level is a trigger to notify the user to generate a supplemental explanation of the problem, notifying the user of the question setting apparatus to generate the supplemental explanation of the problem to guide the students to select a correct answer of the problem; and receiving the supplemental explanation from the user, and sending the supplemental explanation of the problem to the respective student terminals through the network during the test before the test ends.