Tickets

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The answer is 8.

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2 solutions

Dieuler Oliveira
Aug 6, 2014

1 s t 1^{st} Kaplansky's Lemma: The number of ways we can choose p p elements out of a set of n n elements such that there's no two adjacent ones, is: f ( n , p ) = ( n p + 1 p ) f(n,p)={{n-p+1}\choose{p}} Therefore: f ( 35 , 4 ) = ( 32 4 ) α = 32 , β = 4. f(35,4)={{32}\choose{4}} \Rightarrow \alpha=32, \beta=4.

Let the 4 ticket numbers be a , b , c , d a, b, c, d . Now let there be v v ticket numbers less than a a , w w ticket numbers between a a and b b , x x between b b and c c , y y between c c and d d , and finally z z ticket numbers greater than d d .

Now we require that v + w + x + y + z = 35 4 = 31 v + w + x + y + z = 35 - 4 = 31 , where each of w , x w, x and y y must be at least 1 1 . Now let w = w 1 , x = x 1 w' = w - 1, x' = x - 1 and y = y 1 y' = y - 1 . Then we have that v + w + x + y + z = 28 v + w' + x' + y' + z = 28 , where each of the variables can be any value from 0 0 to 28 28 inclusive. This is a then a "stars and bars" type of problem, and so this last equation has ( 32 4 ) \binom{32}{4} solutions.

Thus the desired quotient is 32 4 = 8 \frac{32}{4} = \boxed{8} .

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