Half-life, h = 13 hours Mass initial, a = 38 g B=base for half-life = 2 (a) I(t)=a*B^(-t/h)=a*(B^(1/h)^(-t)=a*(B^(-1/13))^t Substituting values, I(t)=38*(2^(-1/13))^t a=38 g b=2^(-1/13)=0.9480775 (approximately) => I(t)=38*0.9480775^t
(b) I(t)=7 solve I(t)=7=38*0.948077^t Take log on both sides and solve for t t=log(7/38)/log(0.948077) =31.727 hours.
