A test consists of 20 questions, and students are asked to only answer 15 of them. In how many different ways can they choose 15 questions?

Question

Mathematics

Karli Tate

10 March, 04:05

A test consists of 20 questions, and students are asked to only answer 15 of them. In how many different ways can they choose 15 questions?

+2

Answers (1)

Know the Answer?

Gunner Kane · Answer 1

N = 20, r = 15;

n C r = (n * (n - 1) (n - 2) ... (n - r + 1)) / r! =

20 C 15 = (20 * 19 * 18 * 17 ... 8 * 7 * 6) / (15 * 14 * 13 ... * 5 * 4 * 3 * 2 * 1) =

= 15,504

Answer:

They can choose 15 questions in 15,504 ways.