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October 6th, 2014, 02:14 PM  #1 
Newbie Joined: Sep 2014 Posts: 25 Thanks: 0  Combo and permutations questions with better pictures Please help me with 1, 3, 5, 6 Thank you 
October 7th, 2014, 01:21 PM  #2 
Global Moderator Joined: May 2007 Posts: 6,821 Thanks: 723 
Picture is very blurred!

October 7th, 2014, 08:21 PM  #3  
Senior Member Joined: Jul 2014 From: भारत Posts: 1,178 Thanks: 230  Having a look at the first question suck up a lot of my time ! Also, all questions (1,3,5 and 6) are related to permutations and combinations. So, I am solving the fifth one. Taking inspiration from this solution, solve the rest. Quote:
involving "CHOOSING" where order doesn't matter the formula for choosing k objects from n objects is $\displaystyle ^{n}{_{C_k}} = \frac{n!}{\left( k! \times (nk)! \right) }$ where n! is called factorial n & is $\displaystyle n \cdot (n1) \times (n2) \times... \times 1 $ thus number of ways = $\displaystyle ^{12}{_{C_{3}}} = \frac{12!}{( 3! \times 9!)}$ $\displaystyle = 12 \times 11 \times \frac{10}{(1 \times 2 \times 3)} = 220$  

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combo, permutations, pictures, questions 
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