Number series – missing term with doubling increments: 4, 19, 49, ?, 229

Introduction / Context:
The series shows increases whose increments themselves follow a doubling pattern, a frequent exam motif.

Observation / Approach:

• 4 → 19: +15
• 19 → 49: +30 (doubles)
• 49 → ?: +60 (double again)
• ? → 229: +120 (double again)

Step-by-Step Solution:
49 + 60 = 109.

Verification / Alternative check:
Continuing: 109 + 120 = 229 (fits exactly).

Why Other Options Are Wrong:
75, 65, 169, 99 do not preserve the “+15, +30, +60, +120” doubling sequence.

Common Pitfalls:
Trying powers/squares; the constant ratio appears not on the terms but on the differences.

Final Answer:
109