Directions: Find the wrong number in the series. 3, 8, 15, 24, 34, 48, 63
Aptitude
Odd Man Out and Series
Difficulty: Medium
Choose an option
-
A15
-
B24
-
C34
-
D48
-
E63
Answer
Correct Answer: 34
Explanation
### Concept & Logic
The series follows a pattern of squares of consecutive integers minus $1$. Let's verify this.
### Step-by-Step Solution
1. Check the pattern of squares:
- $2^2 - 1 = 4 - 1 = 3$
- $3^2 - 1 = 9 - 1 = 8$
- $4^2 - 1 = 16 - 1 = 15$
- $5^2 - 1 = 25 - 1 = 24$
- $6^2 - 1 = 36 - 1 = 35$ (Wait, the given number is 34)
- $7^2 - 1 = 49 - 1 = 48$
- $8^2 - 1 = 64 - 1 = 63$
2. Alternatively, check the differences:
- $8 - 3 = 5$
- $15 - 8 = 7$
- $24 - 15 = 9$
- The differences are consecutive odd numbers: $5, 7, 9, 11, 13, 15$.
- Next term should be $24 + 11 = 35$. The given term is $34$.
- The term after that would be $35 + 13 = 48$, which is correct.
3. Therefore, $34$ is the wrong number in the series. It should be $35$.
### Exam Strategy & Shortcut
Familiarity with squares and numbers near squares ($n^2-1, n^2+1$) is crucial for solving series questions quickly.
### Common Pitfall
Not checking the term *after* the suspected wrong number to confirm the pattern holds. Always verify that replacing the wrong number fixes the rest of the sequence.
### Final Answer
Therefore, the correct answer is **34**.