(d) Comparing the given equation with standard equation
$y = a\sin{2\pi}\left( \frac{t}{T} - \frac{x}{\lambda} \right) \Rightarrow T = 0.04sec \Rightarrow v = \frac{1}{T} = 25Hz$
Also $(A)_{\max} = \omega^{2}a = \left( \frac{2\pi}{T} \right)^{2} \times a = \left( \frac{2\pi}{0.04} \right) \times 3$
$= 7.4 \times 10^{4}cm/\sec^{2}$