A school water tank drains such that the volume of water remaining after t minutes is given by the linear polynomial V(t)=12.5−0.25t (in kilolitres).
(i) For what value of t will the tank become empty?
(ii) How many minutes after the start of drainage will exactly 3 kilolitres of water remain in the tank?
(iii) Interpret the physical meaning of the zero obtained in part (i) with respect to the situation.