GMAT Problem Solving (PS) | Re: In the following pairs of numbers, which are reciprocals of each other

A number is a reciprocal of another number, if the numbers can be represented as x and\(\frac{1}{x}\)
Lets look at the answer options,
I. 1 and 1 (These are reciprocal numbers)
II. 1/11 and −11 (Two numbers can never be reciprocal if they are of the opposite sign)
III. 5 and\(\frac{\sqrt{5}}{5}\)

Since 5 =\(\sqrt{5}*\sqrt{5}\)
\(\frac{\sqrt{5}}{5}\) =\(\frac{\sqrt{5}}{\sqrt{5}*\sqrt{5}}\) =\(\frac{1}{\sqrt{5}}\)

5 and\(\frac{\sqrt{5}}{5}\) are not reciprocals.
HenceOption A(I only) is the only option which has reciprocal numbers.
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