If a rock is thrown upward on the planet Mars with a velocity of $10 \mathrm{m} / \mathrm{s}$, its height in meters $t$ seconds later is given by $y=10 t-1.86 t^{2}$
(a) Find the average velocity over the given time intervals:
(i) $(1,2]$
(ii) $[1,1.5]$
(iii) $(1,1.1]$
(iv) $[1,1.01]$
(v) $[1,1.001]$
(b) Estimate the instantancous velocity when $t=1.$