Two massless springs with spring constants 2k and 9k , carry 50g...

Maximum velocity is given by {v}_\max = \omegaA $= \sqrt{\dfrac{k}{m}}A$

Here, $\sqrt{\dfrac{{k}_{1}}{{m}_{1}}}{A}_{1} = \sqrt{\dfrac{{k}_{2}}{{m}_{2}}}{A}_{2}$

$⇒ \sqrt{\dfrac{2k}{50 \times {10}^{- 3}}}{A}_{1} = \sqrt{\dfrac{9k}{100 \times {10}^{- 3}}}{A}_{2}$

$⇒ 2{A}_{1} = 3{A}_{2}$

Thus, ratio of amplitude is $\dfrac{{A}_{1}}{{A}_{2}} = \dfrac{3}{2} = 3: 2$.