Homework Help Forum: Pre-Algebra [Combinations]

Posted by mysterychicken on Thursday, June 25, 2009 at 6:05pm.

Need help with these- 1.How many groups of 4 fabrics can be selected from 7 fabrics? 2.The school photographer wants to photograph 3 students from a club with 14 members. How many combinations can be made? 3.Philip wishes to check 2 books out of his school library. If the library contains 800 books, in how many ways might Philip make his choice of books? Thanks -MC

• Pre-Algebra [Combinations] - Damon, Thursday, June 25, 2009 at 6:21pm

  C(n,k) = n!/[ (n-k)!k! ] for example if n = 7 and k = 4 C(7,4) = 7! /[ 3! 4! ] = 7*6*5 *4! /[3*2*1 *4!] 4! cancels top and bottom 6 cancels top and bottom = 7*5 =35 Now try n = 14, k = 3 and n = 800, k = 2

  
  

• Pre-Algebra [Combinations] - mysterychicken, Thursday, June 25, 2009 at 6:21pm

  Nevermind I got all the answers: 1. 35 groups 2. 364 combinations 3. 319,600 choices -MC

  
  

• Pre-Algebra [Combinations] - mysterychicken, Thursday, June 25, 2009 at 6:22pm

  ..Oops just saw that Damon. Thanks! -MC

  
  

Answer this Question

First Name:
School Subject:
Answer: