Question:
If $\sqrt{7}=2.646$ then $\frac{1}{\sqrt{7}}=?$
(a) $0.375$
(b) $0.378$
(c) $0.441$
(d) None of these
Solution:
$\frac{1}{\sqrt{7}}=\frac{1}{\sqrt{7}} \times \frac{\sqrt{7}}{\sqrt{7}}=\frac{\sqrt{7}}{7}$
Given that
$\sqrt{7}=2.646$
So, $\frac{\sqrt{7}}{7}=\frac{2.646}{7}=0.378$
Hence, the correct answer is option (b).