UPSEE Solved Model Paper 4

Difference between sample space and subset of sample space is considered complementary events.
Complementary events are two outcomes of an event that are the only two possible outcomes. This is like flipping a coin and getting heads or tails. ... Rolling a die and getting a 1 or 2 are not complementary since there are other outcomes that may happen (3, 4, 5, or 6).