A student was asked to solve the fraction $$\frac{\frac{7}{3} + 1\frac{1}{2} \text{ of } \frac{5}{3}}{2 + 1\frac{2}{3}}$$ and his answer was $\frac{1}{4}$. By how much was his answer wrong?
Aptitude
Simplification
Difficulty: Medium
Choose an option
-
A1
-
B1/55
-
C1/220
-
DNone of these
Answer
Correct Answer: 1
Explanation
### Concept & Strategy
First, compute the correct value of the given complex fraction using the standard **BODMAS** rules. Then, find the absolute difference between the correct value and the student's incorrect answer ($\frac{1}{4}$) to determine by how much it was wrong.
### Step-by-Step Solution
* **Step 1: Simplify the Numerator**
$$\text{Numerator} = \frac{7}{3} + 1\frac{1}{2} \text{ of } \frac{5}{3}$$
Convert the mixed fraction: $1\frac{1}{2} = \frac{3}{2}$
$$\text{Numerator} = \frac{7}{3} + \left(\frac{3}{2} \times \frac{5}{3}\right) = \frac{7}{3} + \frac{5}{2}$$
Find the common denominator (6):
$$\text{Numerator} = \frac{14 + 15}{6} = \frac{29}{6}$$
* **Step 2: Simplify the Denominator**
$$\text{Denominator} = 2 + 1\frac{2}{3} = 2 + \frac{5}{3} = \frac{6 + 5}{3} = \frac{11}{3}$$
* **Step 3: Calculate the Correct Fraction Value**
$$\text{Correct Value} = \frac{\frac{29}{6}}{\frac{11}{3}} = \frac{29}{6} \times \frac{3}{11} = \frac{29}{2 \times 11} = \frac{29}{22}$$
* **Step 4: Find the Difference**
$$\text{Difference} = \text{Correct Value} - \text{Student's Answer}$$
$$\text{Difference} = \frac{29}{22} - \frac{1}{4}$$
The LCM of 22 and 4 is 44:
$$\text{Difference} = \frac{29 \times 2 - 1 \times 11}{44} = \frac{58 - 11}{44} = \frac{47}{44} = 1\frac{3}{44}$$
Looking at the choices, none of (a), (b), or (c) match $\frac{47}{44}$. Thus, the correct choice is (d).
### Exam Strategy & Shortcut
Always solve numerator and denominator separately in layered fractions to minimize computational errors. Since the correct value is greater than 1 ($\frac{29}{22} > 1$), subtracting $\frac{1}{4}$ will yield a value around $1.32 - 0.25 = 1.07$, which instantly eliminates options (b) and (c).
### Common Pitfall
Students often calculate the difference in reverse order or misinterpret "by how much was his answer wrong" as a percentage error rather than an absolute difference.
### Final Answer
**Therefore, the correct answer is None of these.**