The population $P$ at time $t$ of a rural community is given by the equation $P(t)=1500(3)^{-0.25 t},$ where $t=0$ corresponds to year $1999, t=1$ to year

2000 and so on. What will be the population of this community in year

(a) 2000, (b) 2005, (c) 2015?