Mathematics for IGCSE & O level - Inequalities (Section 1 - No. 45)
If A is older than 11 and less than or equal to 15, which option represents all possible ages of A?
A > 11 and A < 15
A ≥ 11 and A ≤ 15
A > 11 and A ≤ 15
A < 11 and A ≥ 15
解释
Greater than 11 means not equal to, and less than or equal to 15 is a closed boundary at 15.