Question #0de68

1 Answer
Sep 9, 2017

#x=4#

Explanation:

The median is the middle value of a collection when the collection is arranged in order of size.

This implies that if #color(blue)4# is the median then it must be one of the numbers in the collection.
Since #4# is not #ul("explicitly")# a member of #{1,3,7,5,x}#
then it must be #ul("implicitly")# a member by having #x=4#.

In fact if we arrange the sequence by size with #x=4#
we get
#color(white)("XXX")1, 3, x=4, 5, 7#
and, in fact, #x=4# is the median.