Correct Answer - Option 3 : 152
Given: 15 : 135 :: 16 : ? :: 18 : 189
The logic follows here is:
15 : 135 → (15 + 3) × 15 ÷ 2 = 18 × 15 ÷ 2 = 9 × 15 = 135
18 : 189 → (18 + 3) × 18 ÷ 2 = 21 × 9 = 189
Similarly,
16 : ? → (16 + 3) × 16 ÷ 2 = 19 × 8 = 152
⇒ ? = 152
Hence, 152 is the correct answer.