ABC26GN1915 · Surds and Indices

Subject: General Aptitude · Chapter: Surds and Indices · Exam: · Marks: · Difficulty:

What will come in place of both the question marks in the following question? (Bank Recruitment, 2010) $\frac{(?)^{\frac{2}{3}}}{42}=\frac{5}{(?)^{\frac{1}{3}}}$

(a)10

(b)$10 \sqrt{2}$

(c)$\sqrt{20}$

(d)20

(e)210

Answer

Answer (as printed): E

Explanation

Let $\frac{x^{\frac{2}{3}}}{42}=\frac{5}{x^{\frac{1}{3}}}$. $$\text { Then, } x^{\frac{2}{3}} \cdot x^{\frac{1}{3}}=42 \times 5=210 \Rightarrow x^{\left(\frac{2}{3}+\frac{1}{3}\right)}=210 \Rightarrow x=210 \text {. }$$

Explanation as extracted from the printed page; notation may be imperfect.

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