Minor: Some students have memorized the Qur’an.
Major: Everyone who has memorized the Qur’an knows its entirety by heart.
Conclusion: Some students know the entire Qur’an by heart.
The minor tells us about some students, not all students. Although the major is universal, it applies to whoever has memorized the Qur’an; the minor does not establish that every student has done so.
Therefore “All students know the whole Qur’an by heart” is unjustified. A universal major does not enlarge the group identified by the minor.