The position of a particle moving on the $x$-axis is given by $x=t^3+4t^2-2t+5$ where $x$ is in meter and $t$ is in second :-

(i) the velocity of the particle at $t=4 \mathrm{s}$ is $78 \mathrm{m} {\mathrm{s}}^{-1}$
(ii) the acceleration of the particle at $t=4 s$ is $32 \mathrm{m} {\mathrm{s}}^{-2}$
(iii) the average velocity during the interval $t=0$ to $t=4 s$ is $30 \mathrm{m} {\mathrm{s}}^{-1}$
(iv) the average acceleration during the interval $t=0$ to $t=4 s$ is $20 \mathrm{m} {\mathrm{s}}^{-2}$