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Question

If, 5 + 7 = 47, 3 + 8 = 35, 9 + 2 = 29 then 7 + 4 = ?

The correct answer is

39

Solving the Number Puzzle: Finding the Hidden Pattern

The problem presents a series of equations where the standard mathematical operation of addition (+) does not yield the expected sum. This indicates that the '+' symbol represents a different, underlying pattern or operation. We need to analyze the given examples to decipher this hidden rule.

The given equations are:

  • $$5 + 7 = 47$$
  • $$3 + 8 = 35$$
  • $$9 + 2 = 29$$

We need to find the value of $$7 + 4$$ using the same pattern.

Analyzing the Pattern in the Number Puzzle

Let's examine each equation, considering potential relationships between the input numbers and the result. Let the two numbers be 'a' and 'b'. We are looking for an operation $$a \oplus b$$ such that $$a \oplus b = \text{Result}$$.

Let's test a few common pattern types for number puzzles like this:

  • Combining digits in some order.
  • Arithmetic operations involving products, sums, differences, or squares.

Let's try a combination of product and sum. Consider the operation defined as: $$(a \times b) + (a + b)$$.

Let's check if this pattern holds for the given examples:

  1. For $$5 + 7 = 47$$:

    Here, $$a=5$$ and $$b=7$$.

    Applying the proposed pattern: $$(5 \times 7) + (5 + 7)$$

    Calculate the product: $$5 \times 7 = 35$$

    Calculate the sum: $$5 + 7 = 12$$

    Add the product and the sum: $$35 + 12 = 47$$

    This matches the given result.$$

  2. For $$3 + 8 = 35$$:

    Here, $$a=3$$ and $$b=8$$.

    Applying the proposed pattern: $$(3 \times 8) + (3 + 8)$$.

    Calculate the product: $$3 \times 8 = 24$$

    Calculate the sum: $$3 + 8 = 11$$

    Add the product and the sum: $$24 + 11 = 35$$

    This matches the given result.$$

  3. For $$9 + 2 = 29$$:

    Here, $$a=9$$ and $$b=2$$.

    Applying the proposed pattern: $$(9 \times 2) + (9 + 2)$$.

    Calculate the product: $$9 \times 2 = 18$$

    Calculate the sum: $$9 + 2 = 11$$

    Add the product and the sum: $$18 + 11 = 29$$

    This matches the given result.$$

The pattern $$(a \times b) + (a + b)$$ holds true for all the given equations. The '+' symbol in this problem represents this specific operation.

Applying the Pattern to Find 7 + 4

Now, we apply the same pattern to the expression $$7 + 4$$.

Here, $$a=7$$ and $$b=4$$.

Using the pattern: $$(a \times b) + (a + b)$$

Substitute the values: $$(7 \times 4) + (7 + 4)$$

Calculate the product: $$7 \times 4 = 28$$

Calculate the sum: $$7 + 4 = 11$$

Add the product and the sum: $$28 + 11 = 39$$

Thus, $$7 + 4 = 39$$ according to the pattern found in the number puzzle.

Comparing with Options

Let's compare our result with the given options:

  • Option 1: 42
  • Option 2: 45
  • Option 3: 37
  • Option 4: 39

Our calculated result, 39, matches Option 4.

Conclusion

The hidden pattern in this number puzzle is that the operation represented by '+' is actually the product of the two numbers added to their sum.

The pattern is $$a + b = (a \times b) + (a + b)$$.

Using this pattern:

$$7 + 4 = (7 \times 4) + (7 + 4) = 28 + 11 = 39$$.

Operation Calculation (Product + Sum) Result Matches Given?
5 + 7 $$(5 \times 7) + (5 + 7) = 35 + 12$$ 47 Yes
3 + 8 $$(3 \times 8) + (3 + 8) = 24 + 11$$ 35 Yes
9 + 2 $$(9 \times 2) + (9 + 2) = 18 + 11$$ 29 Yes
7 + 4 $$(7 \times 4) + (7 + 4) = 28 + 11$$ 39 N/A (Question)

The final answer is 39.

Revision Table: Key Concepts in Logical Reasoning

Concept Description Relevance to Puzzle
Pattern Recognition Identifying recurring sequences, relationships, or rules in data. Crucial for finding the hidden operation in the number puzzle.
Logical Deduction Using given information and identified patterns to arrive at a conclusion. Applying the discovered pattern to the final expression (7 + 4).
Quantitative Reasoning The ability to understand and work with numerical data and relationships. Essential for analyzing the given equations and calculating the result.

Additional Information: Types of Number Puzzles

Number puzzles and logical reasoning problems often appear in aptitude tests. They test your ability to identify patterns and apply logical thinking. Common types include:

  • Number Series: Finding the next number in a sequence based on a pattern.
  • Alphabet Series: Finding the next letter(s) in a sequence.
  • Coding-Decoding: Deciphering rules used to encode messages or numbers.
  • Analogy: Finding relationships between pairs of numbers or words.
  • Mathematical Operations: Puzzles like this one, where standard operators have unusual meanings.

Practicing different types of logical reasoning questions helps improve problem-solving skills and speed for exams.

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Important Questions from Logical Puzzle

  1. If ‘A’ denotes ‘addition’, ‘B’ denotes ‘subtraction’, ‘C’ denotes ‘multiplication’ and ‘D’ denotes ‘division’, then what will be the value of the following expression?

    6 C (57 B 8) D 7 B 32 A 9

  2. Which two signs need to be interchanged to make the following equation correct?

    63 ÷ 21 – 7 + 28 × 3 = 144

  3. If ‘–’ stands for ‘÷’, ‘+’ stands for ‘×’, ‘÷’ stands for ‘–’ and ‘×’ stands for ‘+’, then 80 – 20 + 10 ÷ 8 × 10 is equal to:

  4. Which two signs need to be interchanged to make the given equation correct?

    3 ÷ 2 - 4 × 5 + 5 = 1
  5. Which two signs need to be interchanged to make the given equation correct?

    20 ÷ 10 × 100 − 10 + 100 = 110
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