Question

3 students are selected from a class of 15 to
attend a seminar. How many different ways can
this choice be made?

Answer 1

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:

$C^{15}_3\\ \\=\dfrac{15!}{3!\cdot (15-3)!}\\ \\=\dfrac{15!}{3!\cdot 12!}\\ \\=\dfrac{12!\cdot 13\cdot 14\cdot 15}{3!\cdot 12!}\\ \\=\dfrac{13\cdot 14\cdot 15}{2\cdot 3}\\ \\=13\cdot 7\cdot 5\\ \\=455$

different ways