The value of $$ \left( \frac{0.896 \times 0.763 + 0.896 \times 0.237}{0.7 \times 0.064 + 0.7 \times 0.936} \right) $$ is
Aptitude
Decimal Fraction
Difficulty: Medium
Choose an option
-
A.976
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B9.76
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C1.28
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D12.8
Answer
Correct Answer: 1.28
Explanation
### Concept & Strategy
Similar to the previous problems, this complex-looking fraction breaks down instantly when you use the **Distributive Property**. The question is designed with "complementary decimals"—numbers inside the brackets that perfectly sum up to $1.000$, neutralizing the complex multiplication.
### Step-by-Step Solution
**Given:**
$$ \frac{0.896 \times 0.763 + 0.896 \times 0.237}{0.7 \times 0.064 + 0.7 \times 0.936} $$
**Calculation:**
* **Simplify the Numerator:** Factor out the common multiplier, $0.896$.
$$ 0.896 \times (0.763 + 0.237) $$
Add the decimals inside the parenthesis. Notice they sum to exactly $1$.
$$ 0.763 + 0.237 = 1.000 $$
Numerator becomes: $0.896 \times 1 = 0.896$.
* **Simplify the Denominator:** Factor out the common multiplier, $0.7$.
$$ 0.7 \times (0.064 + 0.936) $$
Add the decimals inside the parenthesis. They also sum to exactly $1$.
$$ 0.064 + 0.936 = 1.000 $$
Denominator becomes: $0.7 \times 1 = 0.7$.
* **Evaluate the Simplified Fraction:**
$$ \frac{0.896}{0.7} $$
* **Clear the Decimals:** Multiply the numerator and the denominator by $1000$ to work with whole numbers.
$$ \frac{896}{700} $$
* **Divide:** Divide both by $7$:
$896 / 7 = 128$
$700 / 7 = 100$
$$ \frac{128}{100} = 1.28 $$
### Exam Strategy & Shortcut
**Complementary Scanning:** In fraction equations with multiple decimal terms, always check the non-repeated decimals first. $0.763 + 0.237 = 1$ and $0.064 + 0.936 = 1$. The moment you spot this, the entire equation collapses in your head to just $0.896 / 0.7$.
To solve $0.896 / 0.7$ mentally, shift the decimal one place to get $8.96 / 7$. Since $7 \times 1 = 7$, the answer must start with $1$. The only option starting with $1$ and having the correct decimal magnitude is $1.28$.
### Common Pitfall
Failing to recognize that $0.064 + 0.936 = 1.000$. Students sometimes misalign the decimals when adding and think it sums to $0.1$ or $10$, which throws off the final division scale by a factor of 10. Always align decimals vertically:
0.936
+ 0.064
-------
1.000
### Final Answer
**Therefore, the correct answer is 1.28.**