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International Contests
IMO Longlists
1982 IMO Longlists
3
3
Part of
1982 IMO Longlists
Problems
(1)
Show that there exists a point 0 ≤ y ≤ 1
Source: IMO LongList 1982 - P2
3/16/2011
Given
n
n
n
points
X
1
,
X
2
,
…
,
X
n
X_1,X_2,\ldots, X_n
X
1
,
X
2
,
…
,
X
n
in the interval
0
≤
X
i
≤
1
,
i
=
1
,
2
,
…
,
n
0 \leq X_i \leq 1, i = 1, 2,\ldots, n
0
≤
X
i
≤
1
,
i
=
1
,
2
,
…
,
n
, show that there is a point
y
,
0
≤
y
≤
1
y, 0 \leq y \leq 1
y
,
0
≤
y
≤
1
, such that
1
n
∑
i
=
1
n
∣
y
−
X
i
∣
=
1
2
.
\frac{1}{n} \sum_{i=1}^{n} | y - X_i | = \frac 12.
n
1
i
=
1
∑
n
∣
y
−
X
i
∣
=
2
1
.
inequalities
combinatorics proposed
combinatorics