If X = { x 1 ,   x 1 ,   ​ … ,   x n } , the numberof r-comhinations with repetition allowed (or multisets of size r) chosen from X is .

To fill in the blanks in the statement, “If X={x1,x2,...,xn}. The number of r− combinations with repetition allowed (or multisets of size r ) chosen from X is ____.”

Given information:

The statement is given as “If X={x1,x2,...,xn}. The number of r− combinations with repetition allowed (or multisets of size r ) chosen from X is _____.”

A multiset of size r is defined as a set of r number of elements with some of these elements are equal.

If a multiset of size r is formed from the set of n elements such that X={x1,x2,...,xn}, the multiset can be written as a r− combination with repetition, [xi1,xi2,...,xir]