Question 5
Seven examinations have the following candidates:
– Mathematics: An, Bình, Cường and Đạt.
– English: An, Yến, Phương, Giang and Hằng.
– Chemistry: Bình, Yến, Tùng, Dũng and Kiên.
– Literature: Bình, Phương, Lâm and Minh.
– Biology: Giang, Lâm, Nga and Oanh.
– History: Dũng, Minh, Nga and Phong.
– Geography: An, Dũng, Hằng, Kiên, Oanh and Phong.
What is the smallest number of sessions needed so that nobody has two examinations at the same time? Each session may contain one or several examinations.
– Mathematics: An, Bình, Cường and Đạt.
– English: An, Yến, Phương, Giang and Hằng.
– Chemistry: Bình, Yến, Tùng, Dũng and Kiên.
– Literature: Bình, Phương, Lâm and Minh.
– Biology: Giang, Lâm, Nga and Oanh.
– History: Dũng, Minh, Nga and Phong.
– Geography: An, Dũng, Hằng, Kiên, Oanh and Phong.
What is the smallest number of sessions needed so that nobody has two examinations at the same time? Each session may contain one or several examinations.