A herd of deer is introduced on a small island. At first the herd increases...

[LiLi]

...rapidly, but eventually food...? A herd of deer is introduced on a small island. At first the herd increases rapidly, but eventually food resources dwindle and the population declines. It can be shown by means of calculus that the rate R (in deer per year) at which the deer population changes at time t is given by R = -16t^3 + 70t.
(a) When does the population cease to grow? (Round your answer to two decimal places.)