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Question

Three of the following four number-pairs are alike in a certain way and one is different. Pick the number-pair that is different from the rest.

This question was previously asked in
SSC CGL 2018 (Tier 2) Statistics Previous Year Paper (22-feb-2018)
The correct answer is

10 : 98

Finding the Different Number Pair

The question asks us to identify the number-pair that is different from the rest among the given four options. We need to look for a pattern or relationship between the two numbers in each pair.

Let's examine each pair and try to find a rule connecting the first number (let's call it \(n\)) to the second number.

Analyzing Each Number Pair

We will test a common pattern often found in such problems: relating the second number to the square of the first number.

  • Pair 1: 7 : 51

    The first number is 7. Let's square it: \(7^2 = 49\). The second number is 51. We can see that \(49 + 2 = 51\). So, the pattern seems to be \(n : n^2 + 2\).

  • Pair 2: 10 : 98

    The first number is 10. Let's square it: \(10^2 = 100\). The second number is 98. We can see that \(100 - 2 = 98\). So, the pattern here seems to be \(n : n^2 - 2\).

  • Pair 3: 8 : 66

    The first number is 8. Let's square it: \(8^2 = 64\). The second number is 66. We can see that \(64 + 2 = 66\). This pair follows the pattern \(n : n^2 + 2\).

  • Pair 4: 13 : 171

    The first number is 13. Let's square it: \(13^2 = 169\). The second number is 171. We can see that \(169 + 2 = 171\). This pair also follows the pattern \(n : n^2 + 2\).

Identifying the Different Pair

Let's summarize the patterns observed for each number-pair:

Number-Pair First Number (\(n\)) Second Number Relationship to \(n^2\) Pattern
7 : 51 7 51 \(7^2 + 2 = 49 + 2 = 51\) \(n : n^2 + 2\)
10 : 98 10 98 \(10^2 - 2 = 100 - 2 = 98\) \(n : n^2 - 2\)
8 : 66 8 66 \(8^2 + 2 = 64 + 2 = 66\) \(n : n^2 + 2\)
13 : 171 13 171 \(13^2 + 2 = 169 + 2 = 171\) \(n : n^2 + 2\)

From the analysis, we can see that three number-pairs (7 : 51, 8 : 66, and 13 : 171) follow the pattern \(n : n^2 + 2\), where \(n\) is the first number and the second number is \(n^2 + 2\). The number-pair 10 : 98 follows a different pattern, which is \(n : n^2 - 2\).

Therefore, the number-pair that is different from the rest is 10 : 98.

Revision Table: Number Pair Patterns

Number Pair Pattern Found Result
7 : 51 \(n^2 + 2\) \(7^2 + 2 = 51\) (Matches)
10 : 98 \(n^2 - 2\) \(10^2 - 2 = 98\) (Matches)
8 : 66 \(n^2 + 2\) \(8^2 + 2 = 66\) (Matches)
13 : 171 \(n^2 + 2\) \(13^2 + 2 = 171\) (Matches)

The pair 10 : 98 is the odd one out because it follows a different rule compared to the other three pairs.

Additional Information: Number Series and Analogy Questions

Number series and number analogy questions, like this one involving number-pairs, are common in logical reasoning tests. They assess your ability to identify patterns and relationships between numbers.

Common patterns include:

  • Arithmetic progression (adding/subtracting a constant)
  • Geometric progression (multiplying/dividing by a constant)
  • Squares or cubes of numbers
  • Combinations of arithmetic/geometric operations with squares/cubes
  • Prime numbers
  • Fibonacci sequence
  • Operations on digits of the number

To solve these questions, it's helpful to try different types of patterns systemically. Squaring or cubing the numbers is often a good starting point when the numbers grow rapidly, as seen in this number-pair problem.

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Similar Questions

  1. Identify the roll number that doesn't fit this rule.
    Last 3 digits = First 3 digits + 100
  2. If 2 * 3 = 8, 3 * 4 = 81, then 4 * 5 = ?
  3. Find the missing number: 17 : 4914 :: 19 : ?
  4. Find the missing number: $23 : 125 :: 31 : ?$

  5. How many of these roll numbers are palindromes? List: 123321, 654456, 112211, 123456

  6. The second number in the given number-pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) is/are followed in all the number-pairs except one. Find that odd number-pair.

  7. Three of the following four triads are alike in a certain way as they are formed by performing same mathematical operations among themselves and thus form a group. Which triad does NOT belong to that group?

  8. The second number in the given number-pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) is/are followed in all the number-pairs, except one. Find that odd number-pair.

    (NOTE: The relation should be found without breaking down the numbers into its constituent digits)

  9. The second number in the given number pairs is obtained by performing certain mathematical operation(s) on the first number. The same operation(s) are followed in all the number pairs, EXCEPT one. Find that odd number pair.

  10. Three of the following four triads are alike in a certain way as they are formed by performing same mathematical operations among themselves and thus form a group. Which triad does NOT belong to that group?


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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