$\sqrt{\frac{48.4}{0.289}}$ is equal to
Aptitude
Square Root and Cube Root
Difficulty: Easy
Choose an option
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A$1 \frac{5}{17}$
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B$12 \frac{1}{17}$
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C$12 \frac{16}{17}$
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D$129 \frac{7}{17}$
Answer
Correct Answer: $12 \frac{16}{17}$
Explanation
Concept & Math
Similar to evaluating other decimal fractions under roots, equalize the number of decimal places before removing the decimal point. Then extract the whole-number roots and convert the resulting improper fraction to a mixed number.
Step-by-Step Solution
* Given expression: $\sqrt{\frac{48.4}{0.289}}$
* The numerator has 1 decimal place, and the denominator has 3. Equalize them by adding two trailing zeros to the numerator: $\sqrt{\frac{48.400}{0.289}}$
* Once equalized, drop the decimal points entirely: $\sqrt{\frac{48400}{289}}$
* Recognize the core perfect squares: $484 = 22^2$ and $289 = 17^2$.
* Evaluate the root: $\frac{\sqrt{484 \times 100}}{\sqrt{289}} = \frac{22 \times 10}{17} = \frac{220}{17}$
* Convert the improper fraction $\frac{220}{17}$ into a mixed fraction. Divide $220$ by $17$: $17 \times 10 = 170$, and $17 \times 2 = 34$, so $17 \times 12 = 204$.
* The remainder is $220 - 204 = 16$.
* This translates to the mixed fraction $12 \frac{16}{17}$.
Exam Strategy & Shortcut
You can quickly estimate the final division: $220 \div 17$. Since $17 \times 10 = 170$, the quotient is clearly greater than 10 (eliminating Option a). Because $17 \times 13 = 221$, the quotient must be just under 13. This logic points directly to $12 \frac{16}{17}$ without having to perform long division mechanically.
Common Pitfall
A frequent error is dropping the decimal point prematurely without padding, writing $\sqrt{\frac{484}{289}} = \frac{22}{17}$. This directly leads to the incorrect mixed fraction $1 \frac{5}{17}$ (Option a). Always equalize the decimal places first.
Final Answer
Therefore, the correct answer is $12 \frac{16}{17}$.