The displacement (in feet) of a certain particle moving in a straight line is given by $\displaystyle s = t^3/6$, where t is measured in seconds.

(a) Fins the average velocity over the following time periods.

(i) [1,3]

(ii) [1,2]

(iii) [1,1.5]

(iv) [1,1.1]

(b) Find the instantaneous velocity when t=1