The depth ' $d$ ' below the surface of the earth where the value of acceleration due to gravity becomes…
The depth ' $d$ ' below the surface of the earth where the value of acceleration due to gravity becomes $\left(\frac{1}{n}\right)$ times the value at the surface of the earth is $(\mathrm{R}$ = radius of the earth)
Inside the earth, $g^{\prime}=g\left(1-\frac{d}{R}\right)$
$\frac{\mathrm{g}}{\mathrm{n}}=\mathrm{g}\left(1-\frac{\mathrm{d}}{\mathrm{R}}\right)$
Or $\mathrm{d}=\mathrm{R}\left(\frac{\mathrm{n}-1}{\mathrm{n}}\right)$