ABC26GN1480 · Square Roots and Cube Roots
Subject: General Aptitude · Chapter: Square Roots and Cube Roots · Exam: · Marks: · Difficulty:
If $\sqrt{7}=2.645$, then the value of $\frac{1}{\sqrt{28}}$ up to three places of decimal is [SSC-CHSL (10+2) Exam, 2015]
(a)0.183
(b)0.185
(c)0.187
(d)0.189
Answer
Explanation
$$\begin{aligned} & \frac{1}{\sqrt{28}}=\frac{1}{\sqrt{2 \times 2 \times 7}}=\frac{1}{2 \sqrt{7}} \\ & =\frac{\sqrt{7}}{2 \sqrt{7} \times \sqrt{7}}=\frac{\sqrt{7}}{14} \\ & =\frac{2.645}{14}=0.189 \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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