$\mathrm{T}^{\prime}=2 \pi \sqrt{\frac{\ell}{\mathrm{g}_{\mathrm{eff}}}}=2 \pi \sqrt{\frac{\ell}{2 \mathrm{g} / 3}}=2 \pi \sqrt{\frac{3 \ell}{2 \mathrm{g}}}$
$\mathrm{T}^{\prime}=\sqrt{\frac{3}{2}} \mathrm{T}$
$x = 3\,sin\, 20\pi t + 4\, cos\, 20\pi t$ ,
where $x$ is in $cms$ and $t$ is in $seconds$ . The amplitude is ..... $cm$
