Step 10 The probability that a student takes longer than 130 minutes, and is thus unable to complete the exam was determined to be 0.0668. Thus, in a sample of students, it is expected that the portion of students unable to complete the exam will be 0.0668. Multiply this probability by the number of students taking the exam, 80, to determine how many students will not complete the exam, rounding the result up to the nearest integer. students unable to complete exam = 0.0668(sample size of students taking exam) = 0.0668(80) = students