Register
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?
57.9k views
0 votes
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?

User Jclancy
by
8.2k points

1 Answer

0 votes
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.
User Unnati
by
7.8k points
Ask a Question
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.2m questions

11.9m answers

Other Questions

What is .725 as a fraction
How do you estimate of 4 5/8 X 1/3
A bathtub is being filled with water. After 3 minutes 4/5 of the tub is full. Assuming the rate is constant, how much longer will it take to fill the tub?
Write words to match the expression. 24- ( 6+3)
Mr. Jacob is 55 years old and tony is 7 years old. in how many years will mr. Jacobs be 4 times as old as Tony
Link Copied!