3

Part of 1987 Swedish Mathematical Competition

Problems(1)

10 closed intervals, each of length 1, are placed in the interval [0,4]

Source: 1987 Swedish Mathematical Competition p3

Ten closed intervals, each of length

1

, are placed in the interval

[0,4]

. Show that there is a point in the larger interval that belongs to at least four of the smaller intervals.

intervalcombinatorics