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Question

Select the correct combination of mathematical signs to sequentially replace the * signs and balance the given equation.

86 * 54 * 34 * 68 * 2 * 33

This question was previously asked in
SSC CGL 2023 (Tier-II) Paper 1 Previous Year Paper (26-Oct-2023) (Shift-1)
The correct answer is

-, +, ÷, ×, =

Understanding the Equation Balancing Problem

The question asks us to find the correct sequence of mathematical signs to replace the asterisks (*) in the given expression so that the equation is balanced. The expression is: 86 * 54 * 34 * 68 * 2 * 33. We need to select one of the provided options, each offering a different sequence of signs, and test if it makes the left side of the equation equal to 33.

To solve this type of problem, we must apply the BODMAS or PEMDAS rule (Order of Operations) correctly while performing the calculations for each option. The order is Parentheses/Brackets, Orders/Exponents, Division and Multiplication (from left to right), and Addition and Subtraction (from left to right).

Testing the Options for Balancing the Equation

Let's test each option by substituting the signs into the expression and calculating the result.

Option 1: -, +, ÷, ×, =

Substituting these signs sequentially, the equation becomes:

\(86 - 54 + 34 \div 68 \times 2 = 33\)

Now, we follow the BODMAS rule:

  1. Division: \(34 \div 68 = \frac{34}{68} = \frac{1}{2} = 0.5\)
  2. Multiplication: \(0.5 \times 2 = 1\)
  3. Addition and Subtraction (from left to right): \(86 - 54 + 1\)
  4. \(86 - 54 = 32\)
  5. \(32 + 1 = 33\)

So, the equation becomes \(33 = 33\). This option successfully balances the equation.

Option 2: ÷, -, +, ×, =

Substituting these signs, the equation is:

\(86 \div 54 - 34 + 68 \times 2 = 33\)

Applying BODMAS:

  1. Division: \(86 \div 54 \approx 1.5926\)
  2. Multiplication: \(68 \times 2 = 136\)
  3. Addition and Subtraction (from left to right): \(1.5926 - 34 + 136\)
  4. \(1.5926 - 34 = -32.4074\)
  5. \(-32.4074 + 136 = 103.5926\)

So, \(103.5926 \neq 33\). This option does not balance the equation.

Option 3: +, ÷, ×, -, =

Substituting these signs, the equation is:

\(86 + 54 \div 34 \times 68 - 2 = 33\)

Applying BODMAS:

  1. Division: \(54 \div 34 \approx 1.5882\)
  2. Multiplication: \(1.5882 \times 68 \approx 107.9976\)
  3. Addition and Subtraction (from left to right): \(86 + 107.9976 - 2\)
  4. \(86 + 107.9976 = 193.9976\)
  5. \(193.9976 - 2 = 191.9976\)

So, \(191.9976 \neq 33\). This option does not balance the equation.

Option 4: ×, ÷, ×, -, =

Substituting these signs, the equation is:

\(86 \times 54 \div 34 \times 68 - 2 = 33\)

Applying BODMAS:

  1. Multiplication/Division (from left to right):
  2. \(86 \times 54 = 4644\)
  3. \(4644 \div 34 \approx 136.5882\)
  4. \(136.5882 \times 68 \approx 9287.9976\)
  5. Subtraction: \(9287.9976 - 2 = 9285.9976\)

So, \(9285.9976 \neq 33\). This option does not balance the equation.

Conclusion

Based on the step-by-step testing, only the combination of signs in Option 1 balances the given equation.

Option Signs Equation Calculation Result Balances?
1 -, +, ÷, ×, = \(86 - 54 + 34 \div 68 \times 2 = 33\) 33 Yes
2 ÷, -, +, ×, = \(86 \div 54 - 34 + 68 \times 2 = 33\) ≈ 103.59 No
3 +, ÷, ×, -, = \(86 + 54 \div 34 \times 68 - 2 = 33\) ≈ 191.99 No
4 ×, ÷, ×, -, = \(86 \times 54 \div 34 \times 68 - 2 = 33\) ≈ 9285.99 No

Revision Table: Key Concepts

Concept Description
Equation Balancing Finding the correct operators to make the left side of an equation equal to the right side.
Order of Operations The set of rules (BODMAS/PEMDAS) that dictates the sequence in which mathematical operations should be performed.
BODMAS/PEMDAS B/P: Brackets/Parentheses
O/E: Orders/Exponents
D/M: Division and Multiplication (left to right)
A/S: Addition and Subtraction (left to right)

Additional Information: Solving Operator Problems

Problems involving finding the correct mathematical operators are common in logical reasoning and quantitative aptitude tests. Success depends on careful application of the order of operations and systematically testing each option. Here are some tips:

  • Always write down the equation clearly after substituting the signs.
  • Break down the calculation according to BODMAS/PEMDAS.
  • Perform operations step by step to avoid errors.
  • Pay close attention to division by zero (although not applicable in this specific problem, it's a common pitfall).
  • If dealing with large numbers or potential fractions, approximate where reasonable or keep as fractions until necessary. In this case, \(34 \div 68\) resulting in 0.5 or 1/2 was key.
  • Practice with different combinations of numbers and operators.

These equation balancing problems test your arithmetic skills and your ability to follow mathematical rules precisely.

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Similar Questions

  1. Read the given statements and conclusions carefully. You have to take the given statements to be true even if they seem to be at variance from commonly known facts. You have to decide which conclusion/s logically follow/s from the given statements.

    Statements:

    All beaches are sand.

    Some deserts are sand.

    All mountains are rocky. 

    Conclusions:

    (I) At least some beaches are desert.

    (II) At least some sands are rocky.

  2. Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation.

    256 * 4 * 9 * 3 * 14 = 51

  3. Which two signs should be interchanged to make the given equation correct?

    60 × 4 + 9 ÷ 3 - 8 = 34

  4. If '+' means 'division', '-' means 'multiplication', '÷' means 'addition' and '× ' means 'subtraction', then what is the value of the following expression?

    14 - 4 ÷ 133 + 7 × 17

  5. Which two signs should be interchanged to make the given equation correct?

    625 ÷ 25 + 7 × 318 - 112 = 381

  6. Select the correct combination of mathematical signs to sequentially replace the * signs and to balance the given equation.

    5 * 23 * 24 * 4 * 10 * 111

  7. Which of the following interchanges of signs would make the given equation correct?

    100 + 100 × 50 - 2 ÷ 3 = 51 

  8. Which of the following interchange of numbers and signs would make the given equation correct?

    24 × 9 + 6 ÷ 24 - 18 = 22   

  9. Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation.

    11 * 13 * 238 * 17 * 34 = 123 

  10. If '+' means 'subtraction', '−' means 'multiplication', '÷' means 'addition' and '×' means 'division', then what is the value of the following expression?

    23 − 31 + 135 × 15 ÷ 16


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

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

    63 ÷ 21 – 7 + 28 × 3 = 144

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

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

    3 ÷ 2 - 4 × 5 + 5 = 1
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