Permutations vs Combinations

Test Preparation SAT Preparation
1

<p>Can someone explain this to me and how to solve these questions (level 4/5 type I mean)</p>

<p>thanks :)</p>

2

<p>Wheres the question?</p>

3

<p>Permutations - selecting objects where order matters</p>

<p>Combinations - selecting objects where order doesn’t matter</p>

4

<p>p:permutation, c:combination n,r—objects</p>

<pre><code> DISTRIBUTION OF DISTINCT OBJECTS
</code></pre>

<p>NO REPITITION P(n,r) n!/(n-r)!<br>
UNLIMITED REPITITION n^r
RESTRICTED REPITITION P(n:r1,r2,r3…) </p>

<pre><code> DISTRIBUTION OF IDENTICAL OBJECTS
</code></pre>

<p>NO REPITITION C(n,r) n!/(r!(n-r)! )<br>
UNLIMITED REPITITION C(n+r-1,r)
RESTRICTED REPITITION -------</p>