Question 1122713
P=Po*e^(-kt); P/Po=1/2
1/2=e^(-3k)
ln both sides
-0.693=-3k
k=0.231

Let t=48
P=10*e^(-0231*48); that will be e^(-11.088)
P=1.529 x 10^(-4) kg 


Check
48 hours is 16 half lives 
2^(-16)=1.5 x 10^(-5) same as above fraction of the original amount.