7, 14, 55, 110, ?
2023
7, 14, 55, 110, ?
- A.
140
- B.
155
- C.
121
- D.
1255
Attempted by 100 students.
Show answer & explanation
Correct answer: C
Key insight: the sequence is built from pairs where each even-position term is double the previous odd-position term.
Check the pairs: 14 = 7 × 2, and 110 = 55 × 2. So the sequence can be grouped as (7, 14), (55, 110), …
Each pair has the form (x, 2x). Therefore the missing term is the first element of the next pair.
A natural continuation for the first elements is 7, 55, 121. Choosing 121 gives the next pair (121, 242), and 121 is one of the answer choices.
Answer: 121