Answer
Yes
Work Step by Step
Yes, since 6 integers > 5 possible sets of integers whose sum is 15. If 6 integers are selected, then by the pigeonhole principle, two must be from the same subset.
S = {3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
{3, 12}, {4, 11}, {5, 10}, {6, 9}, {7, 8}
5 possible sets of integers whose sum is 15
