Question 1081191
a)1=300(0.8)^t
1/300=(0.8)^t
ln 1/300=ln (0.8)^t=t ln 0.8
t=ln 0.00333/ln 0.8=25.56
b)5^n=.01
ln 5^n=ln .01
n ln 5=ln .01
n=ln 0.01/ln 5=-2.8613531161467861013402131375279
c)250(1.03)^n=400
1.03^n=1.6
ln 1.03^n=ln 1.6
n=ln 1.6/ln 1.03=15.9
d)25=200(0.5)^t/5730
716.25=0.5^t
ln 716.25=ln 0.5^t
t=ln 716.25/ln 0.5=-9.4843194236442672185828361184889
☺☺☺☺