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Question

In the following question, select the odd number pair from the given alternatives.

This question was previously asked in
SSC Stenographer 2017 Previous Year Paper (14-Sep-2017) (Shift 1)
The correct answer is

13 - 168

Finding the Odd Number Pair in Reasoning

This question asks us to identify the number pair that is different from the other three. This type of problem is common in logical reasoning and quantitative aptitude tests, requiring us to find a pattern or rule that connects the numbers in each pair. Three pairs will follow the same rule, while the fourth one will not. That unique pair is the "odd number pair".

Identifying the Pattern in Number Pairs

Let's look at the given number pairs:

  • 7 - 50
  • 11 - 122
  • 15 - 226
  • 13 - 168

We need to find a relationship between the first number (let's call it \(X\)) and the second number (let's call it \(Y\)) in each pair \((X - Y)\). Let's try squaring the first number and see if it relates to the second number.

  • For 7 - 50: \(7^2 = 49\). The second number is 50. \(49 + 1 = 50\). The relationship seems to be \(Y = X^2 + 1\).
  • For 11 - 122: \(11^2 = 121\). The second number is 122. \(121 + 1 = 122\). This pair also follows \(Y = X^2 + 1\).
  • For 15 - 226: \(15^2 = 225\). The second number is 226. \(225 + 1 = 226\). This pair also follows \(Y = X^2 + 1\).
  • For 13 - 168: \(13^2 = 169\). The second number is 168. \(169 + 1 = 170\). The second number is 168, not 170. This pair does NOT follow the pattern \(Y = X^2 + 1\).

Checking Each Number Pair Against the Pattern

Let's verify the pattern \(Y = X^2 + 1\) for all the given options:

Option Pair (\(X - Y\)) Calculation (\(X^2 + 1\)) Expected \(Y\) Actual \(Y\) Follows Pattern?
1 7 - 50 \(7^2 + 1 = 49 + 1\) 50 50 Yes
2 11 - 122 \(11^2 + 1 = 121 + 1\) 122 122 Yes
3 15 - 226 \(15^2 + 1 = 225 + 1\) 226 226 Yes
4 13 - 168 \(13^2 + 1 = 169 + 1\) 170 168 No

Conclusion: Identifying the Odd Pair

As shown in the table and calculations above, options 1, 2, and 3 follow the pattern where the second number is one more than the square of the first number (\(Y = X^2 + 1\)). However, option 4, the pair 13 - 168, does not follow this rule. For \(X=13\), \(13^2 + 1 = 169 + 1 = 170\), but the given second number is 168.

Therefore, the pair 13 - 168 is the odd number pair among the given alternatives because it does not fit the mathematical relationship that connects the numbers in the other pairs.


Revision Table: Number Pattern Reasoning

Concept Description How it applies here
Finding the Odd One Out Identifying the element (number, pair, word, figure, etc.) that does not share a common property or pattern with the rest. We looked for a common mathematical rule among the number pairs.
Number Patterns A sequence or set of numbers related by a specific rule (e.g., arithmetic progression, geometric progression, squares, cubes, prime numbers, etc.). The pattern found was \(Y = X^2 + 1\).
Squaring Numbers Multiplying a number by itself (\(n^2\)). This was the core operation used to find the relationship (\(X^2\)).

Additional Information: Tips for Reasoning Questions

When tackling reasoning questions involving number patterns or odd one out, consider these strategies:

  • Look for common operations: Try basic arithmetic operations (addition, subtraction, multiplication, division) or squaring/cubing numbers.
  • Check differences or ratios: Sometimes the pattern involves the difference between consecutive numbers or the ratio between them.
  • Consider properties of numbers: Look for prime numbers, even/odd numbers, perfect squares/cubes, etc.
  • Test potential rules: Once you think you've found a pattern, test it on all the given options to see which one breaks the rule.
  • Stay calm: These questions require careful observation and systematic testing of possibilities.
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Similar Questions

  1. Four pairs of numbers have been given, out of which three are alike in some manner, while one is different. Choose out the odd one.

  2. Four numbers have been given out of which three are alike in some manner, while one is different. Choose the odd one.

  3. In the following question, select the odd number pair from the given alternatives.

  4. In the following question, select the odd number from the given alternatives.


Important Questions from Number Based

  1. Four number triads have been given, out of which three are alike in some manner and one is different. Select the number triad that is different.

  2. Choose the odd number out of the given options.

  3. Identify the odd one from the following.

  4. Identify the number that is different from the rest.

  5. Four numbers have been given out of which three are alike in some manner, while one is different. Choose the odd one.

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