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Question

Which two signs should be interchanged to correct the given equation?
\(3 \times 6 + 2 - 4 \div 8 = 13\)

This question was previously asked in
RRB ALP/Technician 2018 CBT 2 Electronics Mechanic Question Paper (23-Jan-2019) (Shift 1)
The correct answer is
$\div$ and $+$

Equation Correction: Interchange Signs

The problem requires us to interchange two mathematical signs in the given equation to make it true. The original equation is:

\(3 \times 6 + 2 - 4 \div 8 = 13\)

First, let's evaluate the original equation using the order of operations (PEMDAS/BODMAS):

  • Division: \(4 \div 8 = 0.5\)
  • Multiplication: \(3 \times 6 = 18\)
  • The equation becomes: \(18 + 2 - 0.5\)
  • Addition: \(18 + 2 = 20\)
  • Subtraction: \(20 - 0.5 = 19.5\)

The original equation evaluates to \(19.5\), not \(13\). We need to test the given options.

Testing Sign Interchange Options

The correct answer indicates that interchanging the division (\(\div\)) and plus (\(+\)) signs corrects the equation. Let's verify this.

The signs to be interchanged are \(\div\) and \(+\).

The original equation is: \(3 \times 6 + 2 - 4 \div 8 = 13\).

After interchanging \(\div\) and \(+\), the equation becomes:

\(3 \times 6 \div 2 - 4 + 8 = 13\)

Now, let's evaluate this new equation using the order of operations:

  • Multiplication: \(3 \times 6 = 18\)
  • Division: \(18 \div 2 = 9\)
  • The equation becomes: \(9 - 4 + 8\)
  • Subtraction: \(9 - 4 = 5\)
  • Addition: \(5 + 8 = 13\)

The equation now correctly evaluates to \(13\). Therefore, interchanging the \(\div\) and \(+\) signs is the correct solution.

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Similar Questions

  1. If '+' represents '\(\times\)', '-' represents '+', '\(\times\)' represents '\(\div\)' and '\(\div\)' represents '-', then find the value of the following expression.
    \(6 \div 8 \times 2 - 4\)
  2. What will come in place of the question mark (?) in the following equation, if '+' and '÷' are interchanged and '-' and 'x' are interchanged?
    312 + 6 x 8 - 21 ÷ 169 = ?
  3. What will come in the place of ‘?’ in the following equation, if ‘+’ and ‘-‘ are interchanged and ‘×’ and ‘÷’ are interchanged?
    5 × 39 ÷ 39 + 39 - 5 = ?
  4. If ‘P’ stands for ‘×’ , ‘Q’ stands for ‘÷’, ‘R’ stands for ‘−’ and ‘S’ stands for ‘+’, then what will come in place of the question mark (?) in the following equation?
    70 Q 2 R 5 P 3 S 18 = ?

Important Questions from Maths Operations

  1. Consider the following arrangement that has some missing letters: abab_b_bcb_dcdcded_d The missing letters which complete the arrangement are

  2. Let A3BC and DE2F be four-digit numbers where each letter represents a different digit greater than 3. If the sum of the numbers is 15902, then what is the difference between the values of A and D?

  3. How many integers are there between 1 and 100 which have 4 as a digit but are not divisible by 4?

  4. Let x, y be the volumes; m, n be the masses of two metallic cubes P and Q respectively. Each side of Q is two times that of P and mass of Q is two times that of P. Let u = m / x and V = n / y. which one or the following is correct?

  5. The recurring decimal representation 1.272727... is equivalent to

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