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Question

Select the set in which the numbers are related in the same way as are the numbers of the following set.

(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g., 13 - Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is NOT allowed).

(16, 7, 81)

(24, 16, 64)

The correct answer is (13, 7, 36)

Solving Number Analogy Problems

Number analogy questions test your ability to find the relationship or pattern between a given set of numbers and then apply that same pattern to find a matching set from the options. It's important to remember the rule: operations should be performed on the whole numbers, not on individual digits.

Analyzing the Given Number Sets

We are given two sets of numbers that are related in a specific way:

  • Set 1: (16, 7, 81)
  • Set 2: (24, 16, 64)

Let's try to find the rule connecting the three numbers in each set. Let the numbers in a set be represented as A, B, and C.

Finding the Pattern in Set 1 (16, 7, 81)

Here, A = 16, B = 7, C = 81.

Let's explore possible relationships between A, B, and C. Often, the third number is derived from operations on the first two.

  • Sum of the first two numbers: $A + B = 16 + 7 = 23$. This doesn't directly lead to 81.
  • Difference of the first two numbers: $A - B = 16 - 7 = 9$.

Now, let's see if this difference relates to the third number, 81. We know that $9 \times 9 = 81$, which is $9^2$. So, the relationship could be $(A - B)^2 = C$.

Let's verify this pattern with the second given set.

Verifying the Pattern with Set 2 (24, 16, 64)

Here, A = 24, B = 16, C = 64.

Applying the potential pattern $(A - B)^2 = C$:

  • Calculate the difference between the first two numbers: $A - B = 24 - 16 = 8$.
  • Square the difference: $8^2 = 8 \times 8 = 64$.

The result, 64, matches the third number in Set 2. This confirms that the pattern is (First number - Second number)$^2$ = Third number.

So, the rule is: $C = (A - B)^2$.

Applying the Pattern to Options

Now we will check each option to see which one follows the same rule: $C = (A - B)^2$.

Option 1: (13, 7, 36)

Here, A = 13, B = 7, C = 36.

  • Calculate the difference: $A - B = 13 - 7 = 6$.
  • Square the difference: $6^2 = 6 \times 6 = 36$.

The calculated value (36) matches the third number in the set (36). This option follows the pattern.

Option 2: (48, 39, 18)

Here, A = 48, B = 39, C = 18.

  • Calculate the difference: $A - B = 48 - 39 = 9$.
  • Square the difference: $9^2 = 9 \times 9 = 81$.

The calculated value (81) does not match the third number in the set (18). This option does not follow the pattern.

Option 3: (37, 25, 100)

Here, A = 37, B = 25, C = 100.

  • Calculate the difference: $A - B = 37 - 25 = 12$.
  • Square the difference: $12^2 = 12 \times 12 = 144$.

The calculated value (144) does not match the third number in the set (100). This option does not follow the pattern.

Option 4: (21, 19, 8)

Here, A = 21, B = 19, C = 8.

  • Calculate the difference: $A - B = 21 - 19 = 2$.
  • Square the difference: $2^2 = 2 \times 2 = 4$.

The calculated value (4) does not match the third number in the set (8). This option does not follow the pattern.

Conclusion

Based on the analysis, only Option 1 follows the identified pattern where the third number is the square of the difference between the first two numbers.

Set First Number (A) Second Number (B) Third Number (C) Difference (A - B) Difference Squared $(A - B)^2$ Follows Pattern?
(16, 7, 81) 16 7 81 $16 - 7 = 9$ $9^2 = 81$ Yes (Given)
(24, 16, 64) 24 16 64 $24 - 16 = 8$ $8^2 = 64$ Yes (Given)
(13, 7, 36) 13 7 36 $13 - 7 = 6$ $6^2 = 36$ Yes
(48, 39, 18) 48 39 18 $48 - 39 = 9$ $9^2 = 81$ No
(37, 25, 100) 37 25 100 $37 - 25 = 12$ $12^2 = 144$ No
(21, 19, 8) 21 19 8 $21 - 19 = 2$ $2^2 = 4$ No

Revision Table: Number Analogy Pattern

Concept Description Example (based on this problem)
Number Analogy Identifying a mathematical or logical relationship between numbers in a set and applying it to other sets. Finding the pattern in (16, 7, 81) and applying it to options.
Pattern Identification Analyzing given examples to deduce the rule governing the numbers (e.g., arithmetic operations, squares, cubes, ratios). Finding that the third number is the square of the difference between the first two numbers.
Applying the Pattern Testing the deduced rule on the given options to find the set that fits the same relationship. Checking if $(A-B)^2=C$ holds for each option set.

Additional Information: Types of Number Patterns in Reasoning

Number analogy and series problems often involve various types of patterns. Understanding these can help you identify the rule faster:

  • Arithmetic Progressions: Numbers increase or decrease by a constant difference.
  • Geometric Progressions: Numbers are multiplied or divided by a constant ratio.
  • Difference Patterns: The difference between consecutive numbers follows a pattern (e.g., increasing differences, prime number differences).
  • Square and Cube Patterns: Numbers are squares or cubes, or based on operations involving squares or cubes (like in this problem).
  • Mixed Operations: A combination of addition, subtraction, multiplication, or division might be used in a specific sequence.
  • Digit-based Operations (if allowed): Sometimes operations are performed on the individual digits of the numbers (but this was explicitly disallowed in this question).
  • Positional Patterns: The position of the number in the sequence or set might influence the pattern.

Solving these problems effectively requires careful observation, systematic testing of potential patterns, and practice.

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Important Questions from Letter and Number Based

  1. Select the option in which the numbers are related in the same way as are the numbers of the following set.

    (4, 8, 16)

  2. Select the option that is related to the third number in the same way as the second number is related to the first number.

    23 : 441 : : 28 : ?

  3. Select the option that is related to the third number in the same way as the second number is related to the first number and the sixth number is related to the fifth number.

    12 : 72 ∷ 18 : ? ∷22 : 242
  4. Select the option that is related to the third number in the same way as the second number is related to the first number.

    7 : 56 :: 11 : ?

  5. Select the option in which the numbers are related in the same way as are the numbers of the following set.

    (12, 60, 84)

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