(1 point) Let Q(t) represent the amount of a certain reactant present at time t. Suppose that the rate of decrease of Q(t) is proportional to Q3(t). That is. Q=kQ3, where k is a positive constant of proportionality. a. Suppose Q(0)=81. How long will it take for the reactant to be reduced to one half of its original amount? t= help (numbers) b. Suppose Q(0)=21. How long will it take for the reactant to be reduced to one half of its original amount? t= help (numbers) c. Recall that, in problems of radloactive decay where the differential equation has the form Q=kQ, the half-iffe was independent of the amount of the amount of radicactive material initially present. What happens in the case of Q=kQ3 ? Does half-ife depend on Q(0), the amount initially present