From the wording of the question it seems to me that the teacher wants the student to quote any valid, single, value from within the range that "mystery number" could occupy. Lol, using the phrase "mystery number" instead of a variable, say x, makes me think OP is probably at an early level of math, and probably hasn't studied inequalities yet - but I might be wrong.
I doubt that OP will return to make any more posts now. It seems to me that they just wanted verification that there was a mistake in the question before daring to contact the teacher! But I hope I'm wrong.