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Question

If '+' means '÷', '-' means '+', 'x' means ' - ' and '÷' means 'x', what will be the value of the following expression?
 [{(49×12)-(6÷2)}+(4-3)]÷5

The correct answer is
35

Understanding the Operator Substitution

The problem asks us to evaluate a mathematical expression, but with a twist: the standard arithmetic operators (+, -, ×, ÷) have been redefined.

Here are the given operator substitutions:

  • '+' represents '÷'
  • '-' represents '+'
  • '×' represents '-'
  • '÷' represents '×'

The original expression is: [{(49×12)-(6÷2)}+(4-3)]÷5

Applying the Operator Substitutions

We need to replace each operator in the original expression with its new meaning according to the rules provided.

  1. Replace '×' with '-': The term (49×12) becomes (49 - 12).
  2. Replace '÷' with '×': The term (6÷2) becomes (6 × 2).
  3. Replace '-' with '+': The term (4-3) becomes (4 + 3).
  4. Replace the '-' sign (between the first two terms inside the curly braces) with '+'.
  5. Replace the '+' sign (between the curly braces and the last term inside the square brackets) with '÷'.
  6. Replace the final '÷' sign outside the square brackets with '×'.

After applying all these substitutions, the expression transforms into:

[ {(49 - 12) + (6 × 2)} ÷ (4 + 3) ] × 5

Step-by-Step Evaluation

Now, we evaluate the transformed expression using the standard order of operations (PEMDAS/BODMAS: Parentheses/Brackets, Exponents/Orders, Multiplication and Division, Addition and Subtraction).

  1. Evaluate innermost parentheses:
    • (49 - 12) = 37
    • (6 × 2) = 12
    • (4 + 3) = 7
  2. Substitute these results back into the expression:

    [ {37 + 12} ÷ 7 ] × 5

  3. Evaluate the expression inside the curly braces:

    {37 + 12} = 49

  4. Substitute this result back:

    [ 49 ÷ 7 ] × 5

  5. Evaluate the expression inside the square brackets:

    49 ÷ 7 = 7

  6. Substitute this result back:

    7 × 5

  7. Perform the final calculation:

    7 × 5 = 35

Therefore, the value of the given expression after applying the operator substitutions is 35.

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Important Questions from Mathematical Operations

  1. Select the set, from the given options, in which the numbers are related in the same way as are the numbers of the following sets.

    (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.)

    (6, 13, 78)

    (5, 22, 110)

  2. If + means -, - means ×, × means ÷, ÷ means +, then what will come in place of the question mark (?) in the following equation?

    28 - 6 ÷ 4 + 14 × 14 = ?

  3. In the following number-pairs, the second number is obtained by applying certain mathematical operations to the first number. Which numbers should replace X and Y so that the pattern followed by the two numbers on the left side of :: is the same as that on the right side of :: ?

    (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.)

    X : 649 :: 956 : Y

  4. Which two numbers should be interchanged to make the given equation correct?

    75 ÷ 5 + 15 × 4 - 17 × 3 + (60 ÷ 6) × 10 = 100

    (Note: Interchange should be done of the entire number and not individual digits of a given number.)

  5. If '+' means minus, '-' means multiplication, '÷' means plus, and 'x' means division, then solve the equation: 
    15 - 3 + 10 x 5 ÷ 5

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