- 4
- 5
- 6
- 7

Option 3 : 6

Win over the concepts of Ratio and Proportion and get a step ahead with the preparations for Quantitative Aptitude with Testbook.

**Given: **

\(\frac{1}{2}:\frac{1}{y} = \frac{1}{y}:\frac{1}{{18}}\)

**Calculation: **

⇒ \(\frac{1}{2}{\rm{}} \times \frac{1}{{18}} = \frac{1}{y}{\rm{}} \times \frac{1}{y}\)

⇒ \(\frac{1}{{36}}\) = 1/y^{2}

⇒ y = 6

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