RRB NTPC · Question 100
What number will come in place of question mark in this series? 100, 115, ?, 150, 170, 185 A. 135 B. 130 C. 140 D. 145
Show answer & explanation
Answer: (A) A
Explanation
The differences alternate +15 and +20: 100 +15 = 115, +20 = 135, +15 = 150, +20 = 170, +15 = 185. So ? = 135.