# Basic calculation for all you Math legends - please help

• Mar 29th 2010, 01:41 AM
Basic calculation for all you Math legends - please help
OK,

I've got a question which is mega complicated for me, however thought if anyone could help it would be you guys.

I am going to be submitting an article to say 2000 article directories, now to get maximum exposure from the search engines, the article needs to be as unique as possible. Now lets say that the % of uniqueness I am going for, is 40% unique.

Lets say I have 20 different sentences and for each sentence there are 5 different options, so 20 x 5. The variables of the article get choosen completely at random, so taking this into account what are the odds/% that I will get a 40% unique article each time?

Having a formula would be great, because then I would be able to work out whether I need to increase sentences and options for sentences.

Sorry, I am still not sure about the definition. Let's define an article as a sequence $\langle x_1,\dots,x_{20}\rangle$ with $x_i\in\{1,2,3,4,5\}$. What does it mean for an article $a$ to be at least $n$% unique compares to a set $A$ of other articles? Does it mean that at least 8 elements of the sequence have to be different from the corresponding elements of other articles? Then does it mean that no other article has, for example, a given $x_1$, and no other article has a given $x_2$, and so on until $x_8$? Or no other article has given $x_1,\dots, x_8$ together? Or maybe this means that the given article must differ from every other article in at least 8 positions?