Solve $2\frac{2}{9} + 4\frac{1}{18} - 1\frac{1}{2} = x$
Aptitude
Decimal Fraction
Difficulty: Easy
Choose an option
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A$4\frac{5}{9}$
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B$4\frac{7}{9}$
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C$5\frac{8}{9}$
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D$6\frac{1}{2}$
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E$5\frac{2}{3}$
Answer
Correct Answer: $4\frac{7}{9}$
Explanation
### Concept & Formula
When adding or subtracting mixed fractions, the fastest method is to separate the whole numbers from the fractional parts.
$$A\frac{b}{c} + D\frac{e}{f} = (A + D) + \left(\frac{b}{c} + \frac{e}{f}\right)$$
### Step-by-Step Solution
* **Given Equation:**
$$2\frac{2}{9} + 4\frac{1}{18} - 1\frac{1}{2} = x$$
* **Step 1: Separate Whole Numbers and Fractions**
Group the integers and the proper fractions separately:
$$x = (2 + 4 - 1) + \left(\frac{2}{9} + \frac{1}{18} - \frac{1}{2}\right)$$
* **Step 2: Simplify the Whole Numbers**
$$2 + 4 - 1 = 5$$
* **Step 3: Simplify the Fractions**
Find the Lowest Common Multiple (LCM) of the denominators $9, 18,$ and $2$, which is $18$.
Convert all fractions to have the denominator $18$:
$$\frac{2}{9} = \frac{4}{18}$$
$$\frac{1}{18} = \frac{1}{18}$$
$$\frac{1}{2} = \frac{9}{18}$$
Now, evaluate the fraction part:
$$\frac{4}{18} + \frac{1}{18} - \frac{9}{18} = \frac{4 + 1 - 9}{18} = \frac{-4}{18} = -\frac{2}{9}$$
* **Step 4: Combine Both Parts**
$$x = 5 - \frac{2}{9}$$
To subtract the fraction, borrow $1$ from $5$:
$$x = 4 + 1 - \frac{2}{9} = 4 + \frac{9 - 2}{9} = 4\frac{7}{9}$$
### Exam Strategy & Shortcut
Never convert mixed fractions into improper fractions for addition/subtraction (e.g., $20/9 + 73/18 - 3/2$). That balloons the numbers and invites calculation errors. Always handle the integers first ($2+4-1=5$), then quickly balance the fraction denominators mentally.
### Common Pitfall
Students often convert mixed fractions to improper fractions (like $20/9$), which makes finding common denominators and the final division much more tedious and error-prone. Another mistake is improperly handling negative fractional remainders.
### Final Answer
**Therefore, the correct answer is $4\frac{7}{9}$.**