$(0.75 \times 4.4 \times 2.4) \div 0.6 = x$
Aptitude
Decimal Fraction
Difficulty: Medium
Choose an option
-
A4.752
-
B12
-
C13.2
-
D15.84
-
ENone of these
Answer
Correct Answer: 13.2
Explanation
### Concept & Strategy
For complex decimal multiplication and division, the most efficient approach is to convert decimals into whole numbers or fractions, and leverage cancellation before performing any actual multiplication.
$$ \frac{a \times b \times c}{d} $$
### Step-by-Step Solution
* **Given:**
$$ \frac{0.75 \times 4.4 \times 2.4}{0.6} $$
* **Calculation:** Notice that both $2.4$ and $0.6$ have one decimal place. You can immediately divide them as whole numbers.
$$ \frac{2.4}{0.6} = \frac{24}{6} = 4 $$
* Substitute this simplified value back into the expression:
$$ 0.75 \times 4.4 \times 4 $$
* Use the associative property to multiply $0.75$ and $4$ first, since $0.75$ is $\frac{3}{4}$.
$$ 0.75 \times 4 = 3 $$
* Finally, multiply the result by $4.4$:
$$ 3 \times 4.4 = 13.2 $$
### Exam Strategy & Shortcut
Never multiply straight across when division is involved. Always look for the easiest cancellation path. Spotting that $2.4 \div 0.6 = 4$ turns a messy decimal calculation into a trivial mental math problem: $75\%$ of $4$ is $3$, and $3 \times 4.4$ is $13.2$. This avoids large intermediate decimals entirely.
### Common Pitfall
A common error is multiplying $(0.75 \times 4.4 \times 2.4)$ first. This leads to calculating $3.3 \times 2.4 = 7.92$, and then attempting to divide $7.92$ by $0.6$. This is time-consuming and highly prone to arithmetic mistakes. Always cancel out fractions first.
### Final Answer
**Therefore, the correct answer is 13.2.**