A series is given, in which one term is missing. Choose the correct alternatives from the given ones that will complete the series:
C4, B9, F25, C49, ? , D169
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → I121
Each term is a letter followed by a number, and the two parts follow separate rules.
Numbers: 4, 9, 25, 49, ?, 169 are the squares of the prime numbers 2, 3, 5, 7, ?, 13, so the missing number is \(11^2=121\)
Letters by place number: C (3), B (2), F (6), C (3), ?, D (4). The 1st, 3rd and 5th letters go up by 3: C (3), F (6), so the 5th is I (9); the 2nd, 4th and 6th go up by 1: B, C, D
So the missing term is I121