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Question

Which two signs should be interchanged to make the given equation correct?
\(6 - 2 \times 4 \div 10 + 5 = 6\)

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is
$\div$ and $\times$

Solving Equation by Sign Interchange

The goal is to find which pair of signs, when interchanged in the equation \(6 - 2 \times 4 \div 10 + 5 = 6\), makes it correct.

We will use the order of operations (PEMDAS/BODMAS): Division/Multiplication before Addition/Subtraction, evaluated from left to right.

Original Equation Evaluation

The given equation is \(6 - 2 \times 4 \div 10 + 5 = 6\).

  1. Calculate multiplication: \(2 \times 4 = 8\). Equation becomes \(6 - 8 \div 10 + 5 = 6\).
  2. Calculate division: \(8 \div 10 = 0.8\). Equation becomes \(6 - 0.8 + 5 = 6\).
  3. Calculate subtraction: \(6 - 0.8 = 5.2\). Equation becomes \(5.2 + 5 = 6\).
  4. Calculate addition: \(5.2 + 5 = 10.2\).

The result \(10.2 = 6\) is false. The original equation is incorrect.

Testing Sign Interchange: Option D (\(\div\) and \(\times\))

Interchange the multiplication (\(\times\)) sign and the division (\(\div\)) sign.

The equation transforms to \(6 - 2 \div 4 \times 10 + 5 = 6\).

  1. Calculate division: \(2 \div 4 = 0.5\). Equation becomes \(6 - 0.5 \times 10 + 5 = 6\).
  2. Calculate multiplication: \(0.5 \times 10 = 5\). Equation becomes \(6 - 5 + 5 = 6\).
  3. Calculate subtraction: \(6 - 5 = 1\). Equation becomes \(1 + 5 = 6\).
  4. Calculate addition: \(1 + 5 = 6\).

The result \(6 = 6\) is true.

Conclusion

Interchanging the division (\(\div\)) and multiplication (\(\times\)) signs correctly solves the equation.

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Similar Questions

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Important Questions from Mathematical Operations

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  3. Select the set in which the numbers are related in the same way as are the numbers of the given sets.
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