How many people are there in that room?
(I) If 4 persons leave the room, then there will be less than 15 persons in that room.
(II) If 3 more persons enter the room, then there will be more than 20 persons in that room.

if the statement (I) alone is sufficient to answer the question, but (II) does not answer the question.

if the statement {II) alone is sufficient to answer the question but (I) does not answer the question.

if both the statements (I) and (II) are sufficient to answer the question but neither statement alone is sufficient.

if both the statements (I) and (II) together are not sufficient to answer the question and additional data is required.