Directions: In the following question, insert proper mathematical signs between the figures in the sum: If $\times$ means 'Minus'; $\div$ means 'Multiplied by'; $-$ means 'Plus' and $+$ means 'Divided by', then $16 \div 8 \times 4 - 8 + 4 = ?$

Appeared in: RRB Staff Nurse Jaipur-6th June 2018

Explanation

The problem requires a two-step process: first, substitute the given mathematical symbols, and second, solve the new equation using the BODMAS rule.
The original expression 16 ÷ 8 × 4 - 8 + 4 becomes 16 × 8 - 4 + 8 ÷ 4 after substitution.
Following BODMAS, we first perform division (8 ÷ 4 = 2), then multiplication (16 × 8 = 128).
The expression simplifies to 128 - 4 + 2.
Finally, performing subtraction and addition from left to right gives 124 + 2, which equals 126.

Option A: The value 136 is incorrect. This result could be obtained by misinterpreting the substitution rules or making an error in the order of operations.
Option B: The value 122 is incorrect. This error can occur if the final step 128 - 4 + 2 is incorrectly calculated as 128 - (4 + 2), which would be 128 - 6 = 122. Addition and subtraction should be performed from left to right.
Option C: The value 130 is an intermediate result in the calculation, not the final answer. It is obtained after adding 128 + 2 before subtracting 4. While 128 + 2 - 4 also equals 126, a student might mistakenly stop at 130.

Visual 1: Flowchart: A flowchart illustrating the BODMAS order of operations. It would show 'Brackets' at the top, followed by 'Orders', then 'Division/Multiplication' (on the same level), and finally 'Addition/Subtraction' (on the same level), emphasizing the left-to-right rule for operations on the same level.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain This question tests logical and mathematical reasoning, specifically the ability to follow instructions for symbol substitution and apply the correct order of operations (BODMAS) as background academic context rather than a clinical decision trigger.
While this is a general aptitude question, the underlying skills are crucial for nursing practice.
Nurses must demonstrate meticulous attention to detail and follow protocols precisely, especially during drug dosage calculations, where a misplaced decimal or incorrect order of operations can have severe consequences for patient safety.
This type of logical reasoning is essential for interpreting complex patient data and making sound clinical judgments under pressure.

How to Approach the Question

First, carefully read the question and create a clear key for the symbol substitutions (e.g., write down '÷ means ×', '× means -', etc.).
Rewrite the entire mathematical expression using the new symbols. Do not try to solve it in your head.
Recall the BODMAS acronym to remember the order of operations: Brackets, Orders, Division, Multiplication, Addition, Subtraction.
Systematically solve the new expression, performing one type of operation at a time according to BODMAS.
For operations on the same level (like Division/Multiplication or Addition/Subtraction), always work from left to right.
Double-check your calculation before selecting the final answer from the options.

Concept Tested & Keywords

Concept Tested: This question tests logical and mathematical reasoning, specifically the ability to follow instructions for symbol substitution and apply the correct order of operations (BODMAS).
Stem keywords: mathematical signs, substitutions, BODMAS, order of operations
Lead-in keywords: then

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Practise the full RRB Staff Nurse Jaipur-6th June 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.