The value of $$ \frac{(67.542)^2 - (32.458)^2}{75.458 - 40.374} $$ is
Aptitude
Decimal Fraction
Difficulty: Medium
Choose an option
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A1
-
B10
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C100
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DNone of these
Answer
Correct Answer: 100
Explanation
### Concept & Formula
This problem requires evaluating both the numerator and the denominator independently. The numerator uses the standard difference of squares formula, while the denominator requires straightforward subtraction.
$$a^2 - b^2 = (a - b)(a + b)$$
### Step-by-Step Solution
* **Step 1: Simplify the Numerator**
* $a = 67.542$ and $b = 32.458$.
* Apply $(a - b)(a + b)$: $(67.542 - 32.458)(67.542 + 32.458)$.
* Calculate the sum: $67.542 + 32.458 = 100$.
* Calculate the difference: $67.542 - 32.458 = 35.084$.
* Numerator becomes: $35.084 \times 100$.
* **Step 2: Simplify the Denominator**
* Subtract the given values: $75.458 - 40.374 = 35.084$.
* **Step 3: Solve the Fraction**
* Substitute back into the expression:
$$ \frac{35.084 \times 100}{35.084} $$
* The $35.084$ terms cancel out cleanly.
* You are left with $100$.
### Exam Strategy & Shortcut
When dealing with large decimal numbers in exam questions, look for sums that round to clean multiples of $10$, $100$, or $1000$. The sum of the numerator terms $(67.542 + 32.458)$ equals exactly $100$. Once you notice the denominator evaluates to the exact difference $(35.084)$, you can immediately deduce the answer is the sum factor, $100$.
### Common Pitfall
Getting overwhelmed by the large decimals in the denominator and trying to find a complex algebraic link between the numerator's terms and the denominator's terms, instead of just performing the simple subtraction first.
### Final Answer
Therefore, the correct answer is 100.