Answer:
455 different ways
Step-by-step explanation:
3 students are selected from a class of 15 to attend a seminar.There is no matter in order of these students, so you should use combination's formula:
[tex]C^{15}_3\\ \\=\dfrac{15!}{3!\cdot (15-3)!}\\ \\=\dfrac{15!}{3!\cdot 12!}\\ \\=\dfrac{12!\cdot 13\cdot 14\cdot 15}{3!\cdot 12!}\\ \\=\dfrac{13\cdot 14\cdot 15}{2\cdot 3}\\ \\=13\cdot 7\cdot 5\\ \\=455[/tex]
different ways
