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7
7
Part of
2015 Math Prize for Girls Problems
Problems
(1)
Math Prize 2015 Problem 7
Source:
9/22/2015
Let
n
n
n
be a positive integer. In
n
n
n
-dimensional space, consider the
2
n
2^n
2
n
points whose coordinates are all
±
1
\pm 1
±
1
. Imagine placing an
n
n
n
-dimensional ball of radius 1 centered at each of these
2
n
2^n
2
n
points. Let
B
n
B_n
B
n
be the largest
n
n
n
-dimensional ball centered at the origin that does not intersect the interior of any of the original
2
n
2^n
2
n
balls. What is the smallest value of
n
n
n
such that
B
n
B_n
B
n
contains a point with a coordinate greater than 2?