Simple Harmonic Motion Questions

Two simple harmonic motions are represented by the equations $y_1=10\sin (3\pi t+\pi /4)$ and $y_2=5[\sin (3\pi t)+\sqrt{3}\cos (3\pi t)]$. The ratio of their amplitudes is:

Two identical point masses P and Q, suspended from two separate massless springs of spring constants $k_1$ and $k_2$, respectively, oscillate vertically. If their maximum speeds are the same, the ratio $(A_Q/A_P)$ of the amplitude $A_Q$ of mass $Q$ to the amplitude $A_P$ of mass $P$ is:

The oscillation of a body on a smooth horizontal surface is represented by the equation $X=A\cos (\omega t)$. Which one of the following graphs shows correctly the variation of acceleration $a$ with $t$?